Shale Shaker V71N2 March-April 2020

$12.00 U.S.


Facebook | Twitter | LinkedIn |

The Journal of the Oklahoma City Geological Society Volume 71 Number 2

The Shale Shaker The Shale Shaker is published under the oversight of members of the OCGS Publications Committee, who are responsible for all of the editorial and technical content. Publication production assistance provided by: ART DIRECTOR, PRODUCTION AND DESIGN Theresa Andrews, Visual Concepts and Design, Inc.

OCGS Board Officers President – Patrick Kamann Vice President – Mallory Zelawski Treasurer – Drew Dressler Secretary – Cole Hinds Education Chair – Rosie Gilbert Social Chair – Galen Miller Social Media Chair – Britni Watson Website Chair – Julian Michaels Publications Chair – Dan Costello Past President – Steve Ladner Councilor – Doug Bellis doug.bellis@warwick-energy Membership Chair – Mark Oerkerman

Directors Lesley Evans

AAPG House of Delegates John Brett AAPG Mid-Continent Section Representative Michael Bone

OCGS OFFICES 3409 S. Broadway, Suite 804 Edmond, OK 73013 Phone: (405) 235-3648 | Fax: (405) 235-1766 Website: Staff Michelle Hone

March ~ April 2020 | Page 51

The Journal of the Oklahoma City Geological Society Table of Contents

Shale Shaker Features


A Very Short Virtual Field Trip of the Long Arc of the Remarkable Career of Roger Slatt; Andrew Cullen Geochemical Characterization of the Lower Pennsylvanian Morrow Shale in the Anadarko Basin of Oklahoma; Yagmur Sumer and R. Paul Philp, School of Geosciences, University of Oklahoma, Norman, OK

54 Letter from the OCGS President: Novel Virus Crushes Oil Demand;


Patrick Kamann, President, OCGS Board of Directors


Letter from the Editor: Blast from the Past; Dan Costello, Editor


2020 Centennial Sponsorship Announcement


State of the Industry; Dan Costello


OCGS Membership & New Members


Advertisers Index


A Memorial to Dr. Roger Slatt; Andrew Cullen, Warwick Energy

About the Cover

$12.00 U.S.

Theresa Andrews created the cover of the Shale Shaker. COVER PHOTO: Full crowds at our January and February technical luncheons. The OCGS looks forward to seeing you at our luncheons and social events once we are able to get together again!

3409 S. Broadway, Suite 804 Edmond, O K 73013


Page 52 | Volume 71 Number 2



Turning Prospects into Production

105 N. Hudson, Suite 800 Oklahoma City, OK 73102 (405) 232-9700

Allen Peacock

March ~ April 2020 | Page 53

Letter from the OCGS President

By: Patrick Kamann, President, OCGS Board of Directors

Novel Virus Crushes Oil Demand

new well is around $50 per barrel. With prices at $22 a barrel and oil and gasoline storage filling up, operators will be forced to shut-in production. A Forbes article by Christopher Helman ( Oil Headed To $10 A Barrel As Virus Lockdown Eradicates Fuel Demand ) paints the picture that pric- es could get even worse. Where do we go from here? Many of us experienced the downturn in 2008, 2014, and 2016. Saudi Arabia has flooded the market before. In 1998, they flooded the market in a market share battle with Ven- ezuela, and oil prices dropped to $10 per barrel. In all cases we saw prices improve. The market supply will get in balance with demand and the coronavirus will subside. In the meantime, continue to keep up your relationships with friends and colleagues. As we work from home and adapt to the virtual environment, it can be easy to un- plug from the social aspects of work. It is even easier to neglect your friends down the road at the next company. Please take some time to reach out to your friends and colleagues. A text or phone call asking how they are doing can go a long way to lift their spirits and let them know we are in this together. Our goal at the OCGS is to provide our members with world-class continuing education and networking opportunities.

In times of low oil prices, these services are probably more important than ever. Unfortunately, the speed of the corona- virus spread and the call to practice so- cial distancing has led us to cancel our March and April activities. Although it was disappointing to cancel our events, the board felt the health and safety of our members and instructors needed to be our top priority. The OCGS board is actively discussing our options for May and June. If possible, we will try to reschedule our canceled events later in the year. I want to thank those that attended our January and February luncheon talks by Stephen Sonnenberg and Molly Turko. Molly and Steve gave excellent talks, and we had a record turnout at both events. Additionally, I want to thank Dick Merkel for coming to teach his petrophysics course in February. The attendees I spoke with really enjoyed learning from Dick. As the coronavirus concerns ease, we will get back to holding great luncheon talks and continuing education courses. As I said in the beginning, this truly is an unprecedented time. The sharp fall in oil prices is putting a large amount of stress on our industry. Take care of your fam- ily and yourself, network and hone your geologic skills, and remember we will get through this.

Patrick Kamann

As you all know, the current events occur- ring in our industry are unprecedented. As I write this letter on the 27 th of March, the WTI oil price is just below $22 a barrel. This represents a little more than a 60% drop from the beginning of the year. Con- cerns over the spread of the coronavirus have dramatically decreased the demand for oil across the world. To make mat- ters worse, Russia and Saudi Arabia are increasing their output in a market share war. In an energy survey by the Dallas Federal Reserve, US operators outlined they need between $23 and $36 per bar- rel to break even on operating expenses. Additionally, the price to drill a profitable

Weston Resources, Inc. Michael Weston Smith Geologist 2500 South Broadway, Suite 220 Edmond, Oklahoma 73013 (405) 203 6866

DICK HOWELL Sales Manager 405.315.4206

Page 54 | Volume 71 Number 2

March ~ April 2020 | Page 55

Letter from the Editor By: Dan Costello, Editor

A few months ago I put out an open call in this column for donations or lending of historical issues of the Shale Shaker. I would like to thank numerous OCGS members for reaching out with offers to share their collection, and especially Ray Sorenson of Tulsa. Ray graciously donat- ed two bankers boxes full of issues reach- ing back to the first issue in 1949. I visited him in Tulsa with my wife and he gave us a tour of his extended library, including historical maps and original publications of seminal geologic books dating back to the turn of last century. Quite an impres- sive collection! I’ve enjoyed browsing through the history of the society, as well Blast from the Past

as rereading a few key papers that I’d read while working different parts of Oklaho - ma. Over the next couple issues, I will be shar- ing reproductions of some articles I find particularly interesting. This month’s look back is a column named “Industry Slow- down Creates Educational Opportunities” that was printed in 1973 and again in 1983. This is especially timely given cur- rent market conditions. I find some simi - larities to current thoughts regarding the downturn but also some thoughts that are unique to the era.

Dan Costello

Travis Wilson Bluestem Resources, LLC Consulting Geophysicist 2D & 3D Seismic Interpretation

Kathy Lippert

Geological Mapping & Prospect Generation 405.229.6563 3750 W. Main, Suite #230 Norman, OK 73072

405.848.3750 fax: 848.5932 cell: 229.4070

1000 W. Wilshire Blvd.

Suite 345


Oklahoma City, OK 73116

Page 56 | Volume 71 Number 2

March ~ April 2020 | Page 57

Blast from the Past, cont. Letter from the Editor

Page 58 | Volume 71 Number 2

March ~ April 2020 | Page 59

OCGS Membership & New Members

SOCIETY MEMBERSHIP _____________________________________________________________________________ As of 4/1/20 OCGS 370 Active 59 Associate 13 Emeritus 10 Honorary _____ 397 TOTAL NEW MEMBERS _____________________________________________________________________________









Page 60 | Volume 71 Number 2

WhatYou Missed

Top SecretWWII project sends Oklahoma drillers into British oilfield, cont. Roughn cks of Sherwood Forest


We’re proud to highlight our efforts to set high standards as a neighbor, community partner, environmental steward and employer. It’s all in our new Sustainability Report.


March ~ April 2020 | Page 61


AMemorial to Dr. Roger Slatt July 5, 1941 ~ February 22, 2020 (age 78)

Dr. Roger M. Slatt died peacefully at his home in Norman, OK, with his sons, Andrew and Tom, at his side on February 22, 2020. Roger was 78 years old. Roger was born on July 5, 1941, in San Francisco, CA, to Earl and Helen Slatt. Roger grew up in San Francisco eager to learn about everything offered to him. However, he found time to build friendships that lasted his entire life. Roger’s love for science inspired him to get an A.A. from San Francisco City College in 1961. Soon after, he gained his B.A. from California State University in 1965, followed by M.S. and Ph.D. in Geology from the University of Alaska in 1967 and 1970 respectively. After receiv- ing his Ph.D., he taught geology for eight years at Memorial University of Newfoundland and Arizona State University. After his teaching and research experience, Roger spent 14 years in the petroleum industry as Research Manager with Cities Service Research, ARCO Research, andARCO International Oil and Gas Co. before joining Colorado School of Mines as professor and head of the Geology and Engineering Department in 1992. Eight years later, Roger and Linda moved to Norman when he was named Director of the School of Geology and Geophysics at University of Oklahoma, holding this

Dr. Roger Slatt

position until 2006. Leaving the directive of the School allowed Roger to focus solely on teaching, research, and his students through his Reservoir Characterization Institute, founded in 2003. Roger was Gungoll Family Chair Professor in Petroleum Geology and Geo- physics at University of Oklahoma. Dr. Slatt was a tireless worker and passionate geologist. There is probably no other place where he was happier and more energetic than the field. He was always eager to pass on his love for rocks and outcrops to his students. He published approximately 150 articles and abstracts and is author/co-author/editor of six books on a wide range of petroleum geology topics. Considered an industry expert, Roger has been an AAPG and SPE Distinguished Lecturer, and presented courses internationally for industry and government organiza- tions. He is the recipient of the AAPG Distinguished Service Award, the Esso Australia Distinguished Lecturer in Petroleum Geology, AAPG Honorary Membership, AAPG Grover Murray Distinguished Educator Award, Society of Exploration Geophysicists (SEG) Special Commendation Award, and most recently the 2012 Jules Braunstein Memorial Award for co-authoring a poster with colleague Younane Abousleiman on ‘Merging sequence stratigraphy and geomechanics for unconventional gas shales”. He has graduated more than 100 M.S. and Ph.D. students while at OU. In addition to his illustrious career, Roger was a loving husband to his wife, Linda, who occasionally accompanied him on his inter- national consulting or teaching travels. Their home reflected their love of travel and different cultures by displaying items from their travels. He also enjoyed the time he spent with his sons. For instance, an August 2018 road trip with Andrew for some Montana fishing, visiting [and droning] old project sites, and then on to grandson Alexander and Dani’s wedding in Las Vegas, NV. He supported and loved his sons and grandchildren on their endeavors, such as opening Fancy That restaurant with Tom in downtown Norman. Roger loved to take friends to Fancy That to enjoy his son’s dishes. Fishing was Roger’s favorite way to get away and just relax. Every summer, he would head to Montana, Idaho or Wyoming for a week of quality fishing with his longtime friends. He was eager to try new foods on his travels but oysters and chicharron (pork skin) remained two of his favorite foods. Roger passed away peacefully in his home after complications of an illness treated since 2017. He will be remembered as an excellent geologist, but moreover as a lifelong mentor to his students. He was a pioneer in the Oil and Gas Industry and a leading figure in the geoscience community. Roger was a staunch supporter of his international students. He had a love for animals and would also support non-profit organizations that aided animal wellbeing and placement such as ASPCA. He also was an advocate in the fight against cancer; St. Jude Children’s Re - search Hospital was one of his favorites. Should friends desire, contributions honoring Roger’s memory can be made to OU Foundation supporting Colombian and Venezuelan students. For more information about OU Foundation donations please contact Yoana Walschap at Donation instructions for SPCA and St. Jude’s can be found at and

Page 62 | Volume 71 Number 2

Virtual FieldTrip

By: AndrewCullen

A Very Short Virtual Field Trip of the Long Arc of the Remarkable Career of Roger Slatt. As a geologists we conceptualize and present much of our work pictorially. Ancient but true, a good picture is worth a thousand words. From glacial outwash, to deep marine fans, to mudrocks, Roger was always about outcrops. To go with Roger Slatt’s obituary in this issue of the Shale Shaker, here are a few images that highlight the non-linear evolution of remarkable geoscientist. So for any of you wondering what to do you with your life, consider the following and the go LIVE it: 1. Roger didn’t rev-up his academic career until he was 51 years old and didn’t arrive at OU until he was 65 & was just getting started! Nearly half of his 5820 citations are after 2015. 2-3. Roger began his journey studying glacial outwash sediments and geochemistry in Alaska, MS and PhD.

Roger Slatt’s Citations

2) Taku Glacier and outwash plain: MSc. 1967

3) Reid Glacier one of ten glaciers studied: PhD 1970

March ~ April 2020 | Page 63

AVery Short Virtual FieldTrip of the Long Arc of the Remarkable Career of Roger Slatt, cont. Virtual FieldTrip

4. He work in Newfoundland on the provenance & petrology of Quaternary clays sand sand. 5. At Arizona State he published on the Yavapi Group Precambrian iron formations in Arizona. 6-7. Roger spent several decades working on outcrops of deepwater sandstones in Arkansas and New Zealand.

4) Avalon Peninsula, Newfoundland 1970-74

5) Precambrian Iron Formation Arizona years 1974-1978

6) Jackfork Sandstone turbidites, Arkansas (1991-2012)

7) Mount Messenger turbidites, New Zealand (1994-2002)

Page 64 | Volume 71 Number 2

8. In nearly a decade of work on the Woodford Shale, he and his students integrated chemostratigraphy, geomechanics, seismic attributes with regional geology the help industry understand Oklahoma’s premier shale gas play. 9-10. Roger will be missed, but the beat goes on in the hearts of his academic progeny.

8) Woodford Shale, Oklahoma 2011-2020

9) And the Beat Go On 2020….

March ~ April 2020 | Page 65

By: Yagmur Sumer Gorenekli and R. Paul Philp, School of Geosciences, University of Oklahoma, Norman, OK. 73019. Oil and Gas Exploration Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale In The Anadarko Basin Of Oklahoma ABSTRACT The Morrow Formation is one of the most widespread units of Early Pennsylvanian age in the Anadarko Basin and has been one of the most productive oil and gas reservoirs in the Basin since the 1950s. Rock-Eval pyrolysis indicated Morrow source rocks are fair to good source rocks, typically charac- terized as a thermally mature Type-III kerogen with gas generating capacity and limited oil potential. Biomarker data show the Morrow is composed of mixed organic matter with pronounced terrestrial input deposited in a near-shore/transitional environment subjected to periodic terrigenous influx. The abundance of 17α(H)-norhopane in some of the rock extracts indicated increasing carbonate content, or evaporitic conditions. Relatively high concen - trations of rearranged hopanes suggest the Morrow was deposited under clay-rich, brackish/freshwater conditions in a suboxic environment. The pres- ence of 18α(H)-oleanane and 1,2,7-trimethylnaphthalene (TMN) suggests a contribution from angiosperms that evolved long before the Cretaceous or a sister-group of angiosperms that shared common characteristics with contemporary angiosperms. The presence of 25-norhopanes in multiple source rock samples was interpreted as paleo-seepage from an ancient heavily biodegraded reservoir or in-situ biodegradation of oil in fissures and fractures of the shale. Polycyclic aromatic hydrocarbons (PAHs) such as fluoranthene, benzopyrenes, benzofluoranthenes, benzo(a)anthracene, triphenylene and chrysenes in the Morrow source rocks indicate paleo-wildfires were part of the terrestrial ecosystem during Early Pennsylvanian time.

Introduction In recent years exploration and produc- tion in Oklahoma has been dominated by activities in the prolific SCOOP and STACK areas with many other poten- tial source rocks, including the Morrow shale, being overlooked. The Morrow is a Lower Pennsylvanian basal transgressive shale sequence with discontinuous sand- stone reservoirs and thin limestone units widely distributed within Arkansas, Okla- homa, Texas, Kansas, Colorado, Nebras- ka, Wyoming and South Dakota (Fig. 1; Andrews, 2008; Higley et al., 2014). It is an important source rock in the Anadarko Basin (Hatch et al., 1987) with an average thickness of approximately 1500 ft. and more than 60 percent shale and mudstone (Wang and Philp, 1997). The Morrow For- mation has an asymmetric character and is over 4000 ft. thick in the deep trough of the Anadarko Basin, progressively thinning through the Panhandle where the sediments are around 300 ft. thick (Adler et al., 1971). The Morrow is typically overlain by the “Thirteen Finger Atoka Limestone” and underlain by the Springer Formation (Andrews, 1999). The Mor- row-Springer boundary has always been

controversial but is considered a regional unconformity surface. The Morrow Shale is typically character- ized as a Type-III gas-prone kerogen but can be oil prone. Higley et al. (2014) not- ed TOC values of Morrowan Shales from 14 wells in the Anadarko Basin ranged from 0.48 to 10.71 wt.% with an average of 1.72 wt.%. Hydrogen index (HI) values are relatively low ranging from 15 to 179 and averaging 46 mgHC/gTOC. Maturity of the Morrow varies with depth ranging from 2.5% Ro in the deeper Anadarko Basin to 0.5% Ro in northwestern Okla- homa (Andrews, 1999). The present study provides a detailed geochemical analysis of the Morrow Shale within the Anadarko Basin. A secondary objective is related to an evaluation of the somewhat unusual occurrence of oleanane and demethylated hopanes in the Morrow Shale. Geological Background Geologic History of the Anadarko Basin The asymmetric shaped Anadarko Basin, located in the southern Midcontinent, is the deepest interior cratonic basin within

North America, with almost 40,000 ft. of Paleozoic sedimentary rocks overlying 20,000 ft. thick Cambrian igneous rocks at the southern margin of the basin (Johnson, 1989). It has a very complex depositional and tectonic history and formed because of the Pennsylvanian epeirogeny, during which a series of major uplifts created smaller basins, including the Anadarko Basin. The Pennsylvanian period, during which the Morrow Formation was deposited, was marked by major changes in the Anadarko Basin (Johnson, 1989). The North Ameri- can Plate collided with the Gondwana Plate along the Ouachita trough resulting in a change of tectonic style in the basin from extension to compression (Wang and Philp, 1997). The Amarillo-Wichita Mountains were uplifted during this pe- riod and to the north, thick Pennsylvanian sediments resulted from high subsidence and sedimentation rates (Wang and Philp, 1997; Fig. 2). Stratigraphy of the Morrow Formation The Pennsylvanian Morrow Formation is a basal transgressive unit (Forgotson et al.,

Page 66 | Volume 71 Number 2

Figure 1. Location Map of the Anadarko Basin and sample locations (Modified from Cardott, 2012)

Figure 2. Diagrammatic North-South Cross Section of the Deep Anadarko Basin (Modified from Ball et al., 1991)

March ~ April 2020 | Page 67

Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale InThe Anadarko Basin Of Oklahoma, cont. Oil and Gas Exploration

Table 1. Sample names, depths and locations of the Morrow source rock samples

graphic relation between the Morrow and the Springer is completely conformable. In this study, “Morrow Formation” is used for the rock succession from the top of the Mississippian Springer Formation to the bottom of the Atokan Thirteen Finger Limestone (Abels, 1958; Andrews, 1999). The Morrow Formation was deposited fol- lowing several transgressive and regres- sive cycles caused by tectonic and glacio- eustatic effects during early Morrowan time (Al-Shaieb et al., 1995). The study area is predominantly associated with shallow marine conditions while some lo- calized areas show a stratigraphic transi- tion into subaerial depositional conditions (Andrews, 1995). The lithology is mainly characterized by shallow marine fine clas - tics and discontinuous channel sandstones formed following periodic sea level fluc - tuations and sediment influx (Bowen and Weimer, 2003; Higley et al., 2014). Methodology Study Area and Sample Locations Three sets of samples have been analyzed in this study (Fig. 1). The first set of 15 source rock samples (referred to as MOR herein), from various wells and depths in the Anadarko Basin, was originally ex- amined by Wang (1993). The second set of 30 samples (labeled A-1 to A-30), col- lected as chips at 1 ft. intervals, were from the Kephart-1 well, in Blaine County, Oklahoma. The core is comprised of the Morrow Formation and was mainly black shale with alternating carbonate and silt- stone layers. The third set contained two samples (H-2 and H-3) from the Laverne- State-1 well drilled by Gulf Oil Com- pany in Harper County, Oklahoma were obtained from the Oklahoma Petroleum Information Center (OPIC). Depth and lo- cation of the samples are given in Table 1 and Fig. 1.

1966), conformably overlain by the “Thir- teen Finger Limestone” of the Atoka For- mation and unconformably underlain by the Springer Formation (Andrews, 1999) in most of the Anadarko Basin. Bowen

and Weimer (2003) suggested that Mis- sissippian carbonates are separated from the Morrow by an angular unconformity while Andrews (1995) mentioned that in the shallower parts of the Basin this strati-

Page 68 | Volume 71 Number 2

Table 2. Rock-Eval Pyrolysis Results of the Kephart-I and Laverne-State-I Well Samples

Experimental Procedure Sample Treatment and Extraction

cantly different (Wang, 1993). Thus, in this study, S1 and S2 results were used as they were but Tmax values were con- verted to Rock-Eval Tmax as proposed by Wang (1993). The older system did not produce a S 3 peak, and hence no oxygen index (OI) values, for Wang’s (1993) sam- ples (See Table 2 for Rock Eval data from Kephart-1 and Laverne State-1 wells). Extraction and fractionation Crushed samples were extracted using a Soxhlet extraction system, the extracts quantified and subsequently fractionated into asphaltenes, saturates, aromatics, and polars using conventional geochemical techniques. Gas Chromatography and Gas Chroma - tography-Mass Spectrometry Aliphatic and aromatic fractions were

analyzed by gas chromatography using an Agilent Technologies 6890 Gas Chro- matograph (GC) equipped with a fused silica capillary column was a 60 m long DB-5MS model silica column with 0.32 mm i.d. and 0.032 mm thick coating. Gas chromatography-mass spectrometry used an Agilent Technologies 5975 XL mass selective detector (MSD) equipped with a J&W Scientific DB-5MS 122-5562 fused silica column. Results and Discussion Source Rock Characterization Source rock characteristics are initially based on bulk geochemical data such as total carbon content (TOC), thermal ma- turity and kerogen type. The rock samples from Kephart-1 and Laverne-State-1 wells were screened by Rock-Eval pyrolysis and the data are summarized in Table 2. High

The core chips were rinsed thoroughly eliminate potential organic contaminants, and then crushed using a Spex 8000 Mixer/Mill to a fine powder with grain size smaller than 0.425 mm (US Standard mesh No. 40). Rock Eval Pyrolysis Core and cuttings from the Kephart-I and Laverne-State-1 well were screened by GeoMark Petroleum Services Ltd. using traditional Rock-Eval pyrolysis (Espitalié et al., 1977). The source rock samples of Wang (1993) were previously character- ized by an older Rock-Eval type system (Wang, 1993). While S 2 results of these two instruments are very similar, the T max results of these instruments are signifi -

March ~ April 2020 | Page 69

Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale InThe Anadarko Basin Of Oklahoma, cont. Oil and Gas Exploration


3b Figure 3a. Pseudo-van Krevelen Diagram Showing Kerogen Type of the Morrow; 3b. S 2 vs. TOC plot used to determine kerogen Type of the Morrow source rock samples in the Anadarko Basin.

Page 70 | Volume 71 Number 2

Kerogen Classification Morrow Shale kerogens were character- ized by plotting HI and OI values on a Pseudo-van Krevelen diagram (Fig. 3). HI values from the Wang (1993) study ranged from 7 to 155 mgHC/gTOC, with an average of 64 mgHC/gTOC. The HI values of the Kephart-1 core vary between 32 to 160 mgHC/gTOC with an average of 62 mgHC/gTOC and the Laverne- State-1 core HI values are 570 and 33 mgHC/gTOC for H-2 and H-3, respec- tively. Based on HI values, the Kephart-1 samples can be characterized mainly as Type-III kerogen derived from woody ter- restrial plants, and potentially a gas source if appropriate conditions prevail (Fig. 3a). Based on the S 2 vs. TOC plot (Cornford et al., 1998) most of the Morrow source rock samples are Type-III kerogens with a few inert Type-IV kerogens (Fig. 3b). Cau- tion always needs to be exercised when interpreting Rock Eval data to remember that the HI/OI plots are showing the data based on current maturity levels and are not necessarily reflecting the nature of the original source materials as a result matu- rity impact on the original source materi- als. Thermal Maturity Source rock maturity was assessed by using T max values, calculated vitrinite reflectance (%R c ), and production in- dex values (Table 2). T max values of the Morrow samples ranged from 422 O C to 456 O C with an average 439 O C indicat- ing maturity ranging between immature to mature (late-oil window) stage (Peters and Cassa, 1994). Maturity of the Morrow appears to decrease from the southeast to the northwest of the study area. In Mc- Clain County the Morrow is currently at 15,000 ft. but at 7000 ft. depth in Harper County, hence maturity shows significant variations in different parts of the basin. The average T max value of the Kephart-I

S1 results may be indicative of contami- nation from drilling fluid additives or non- indigenous hydrocarbons that were ex- pelled and migrated from another source rock. Samples with S1/TOC ratio >1.5 ratio were rejected from further analyses due to possible contamination from non- indigenous oil or drilling additives (Smith, 1994). Maturity and/or weathering will re- sult in a reduced S 2 peak. Therefore T max values were ignored if S 2 was less than 0.5 mg HC/g rock since the peak often appears broad and flat making it difficult to determine an accurate Tmax value. Al- though T max values can range from 300°C to 590°C, values below 400°C are gener- ally considered anomalous if the produc- tion index (PI) of the sample is above 0.2 and maybe related to heavy hydrocarbon staining (Nuccio and Barker, 1989). Total Organic Content Source rocks are classified as poor if TOC values are < 0.5 %; fair if TOC values are between 0.5%-1%; good if TOC values range between 1%-2%; and excellent if TOC values are > 4% (Peters, 1986; Al- Atta et al., 2014). The TOC content of the 15 source rock samples from the Wang (1993) study ranged from 0.99% - 2.53% with average of 1.55%. The average TOC value of the Kephart-1 core samples was 1.32% with a minimum value of 0.29% at 8494 ft. and maximum of 2.85% at 8532 ft. The TOC values of the two source rock samples from Laverne-State-1 core in Harper County (Fig. 3) were 19.6% at 7012 ft. and 6.3% 7029 ft., respectively. Based on TOC values, the Morrow Shale in the study can be classified as a good source rock in terms of organic richness although the variability of the TOC values also illustrates the heterogenic and com- plex character of the Morrow Formation due to periodic fluctuations in organic matter resulting from frequent sea level changes throughout the depositional his- tory.

core is 454 O C and ranges between 436 O C to 463 O C and the average T max value of the Laverne-State-I core is 436 O C. Based on T max data, the Morrow is thermally ma- ture between the early oil-window and the wet-condensate zone for the core samples analyzed in this study. Calculated vitrinite reflectance, %R c , can be determined from T max values using the conversion formula (R c % = [(0.018)*T max ] -7.16) proposed by Jarvie et al. (2001). The average %R c for 15 of the source rock samples was 0.73 and ranged from 0.44 %R c at 7943 ft. and 1.05%R c at 10816 ft. varying from imma- ture to the late-oil window. Combining production index data with T max shows that the Morrow samples demonstrate a transi- tional trend between immature to late oil- window (Fig. 4). Biomarker Characteristics Biomarkers are organic compounds in sedimentary rocks and oils whose carbon skeletons are related to functionalized compounds present in formerly living or- ganisms (Waples and Machihara, 1991) and provide valuable information about type of organic matter, depositional condi- tions, age-dating, thermal maturity, migra- tion history and degree of biodegradation (Wang et al., 2004). Several families of biomarkers were monitored in this study and described in the following sections. Important biomarker parameters derived from isoprenoids, tricyclic terpanes and hopanes are summarized in Table 3. n-Alkanes and Isoprenoids The Morrow extracts are typically charac- terized by bimodal n-alkane distributions, with unimodal or trimodal distributions in more mature and/or biodegraded samples (Fig. 5). The presence of n-alkanes >C 25 in samples indicates a near-shore transi- tional (mixed type) depositional environ- ment periodically subjected to terrigenous influx. Samples with a narrow unimodal

March ~ April 2020 | Page 71

Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale InThe Anadarko Basin Of Oklahoma, cont. Oil and Gas Exploration

Figure 4. T max vs. PI plot showing hydrocarbon generation zones of organic matter in the Morrow Shales

n-alkane distribution, n-C 17 /n-C 18 pre- dominance, and lack of higher molecular weight n-alkanes may indicate low terrig- enous input or elevated maturity. Carbon preference index (CPI) values for most of the Morrow source rock samples are ap- proximately 1 due to maturity level and high clay content of the samples. MOR- 33 from Roger Mills and MOR-57 from Dewey County have CPI values less than 1 which may indicate increasing carbon- ate content. The terrigenous/aquatic ratio (TAR; Bour - bonniere and Meyers, 1996), indicates the relative proportions of terrigenous vs. aquatic organic matter input into the depositional environment. Secondary pro- cesses, such as biodegradation or thermal maturity can impact the ratio (Peters et al., 2005). TAR= C 27 +C 29 +C 31 ___________ C 15 +C 17 +C 19 TAR values for the Morrow source rocks

range between 0.03-1.63 (ave. 0.30) with average TAR values for the Kephart-I and Laverne-State-I wells being 0.08 and 0.2, respectively. In general, variations in the TAR values at each location support dy- namic depositional conditions of the Mor- row with periodic terrigenous influx. The Pr/Ph ratios for most the Morrow source rock samples from theWang (1993) study are greater than 1 and indicate the Morrow was deposited in a transitional depositional environment supplied with both terrestrial and marine organic input and alternating oxic/sub-oxic conditions (Didyk et al., 1978; Shanmugam, 1985; Waples, 1985). The Pr/Ph ratios for Keph- art-I samples are generally greater than 1 throughout the core, except the 8516- 8495 ft. interval indicating that anoxic conditions prevailed during deposition of this interval. The Pr/Ph ratios for the core samples, H-2 and H-3, from Laverne- State-I well are 4.35 and 1.42, respective- ly, indicating that oxic to suboxic deposi-

tional conditions with terrigenous organic matter input prevailed during deposition of the Morrow in Harper County. The cross plot of Pr/ n -C 17 vs. Ph/ n -C 18 show the Morrow samples plot in a transitional depositional setting with mixed organic matter (Fig. 6). The plot also shows that the samples were not biodegraded since if they were, Pr/n-C 17 vs. Ph/n-C 18 ratio would be expected to be elevated since n-alkanes are removed before the isopren- oids in biodegraded organic matter. Tricyclic Terpanes Terpanes are ubiquitous in geological samples and provide information related to maturity, depositional environment, or- ganic input and migration as well as be- ing used for correlation purposes (Wang et al., 2012; Zhang and Philp, 2012; Tao et al., 2015). In crude oils and source rock extracts the tricyclic terpanes exist as a homologous series ranging from C 19 to at least C 40 with most emphasis typi-

Page 72 | Volume 71 Number 2

Figure 5. Gas Chromatograms showing the n-alkane distributions of the Morrow Shale samples (Pr: pristane, Ph: Phytane)

March ~ April 2020 | Page 73

Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale InThe Anadarko Basin Of Oklahoma, cont. Oil and Gas Exploration

Figure 6. Cross plot of Pr/n-C 17 vs. Ph/n-C 18 shows the Morrow samples falling into mixed organic matter zone (n-C 17 : C 17 normal alkane; n-C 18 :C 18 normal alkane)

cally placed on the more readily resolv- able members of the series in the range C 19 - C 30 . These compounds are generally determined by GCMS and single ion mon- itoring of the characteristic ion at m/z 191. The Morrow extracts are generally char- acterized by higher hopane concentrations relative to tricyclic terpanes while some of the highly mature samples are dominated by tricyclic terpanes (Fig. 7). Ourisson et al. (1982) and Heissler and Ladenburger (1988) suggested that the precursors of the tricyclic terpanes (

nadian County, MOR-41 from Blaine County and MOR-75 sample from Wood- ward County are close to being greater than 1. The results show that MOR-39 and MOR-41 samples probably belonged to a transitional depositional environment with a mixed type of terrestrial and ma- rine organic matter input while MOR-75 was probably deposited in a terrestrial en- vironment. The C 19 /C 23 and C 20 /C 23 values for the MOR-33 sample from Roger Mills County, MOR-86 sample from Woodward County and the MOR-68 sample from Dewey County are less than 0.25 with C 23 tricyclic terpane/ C 30 hopane ratios greater than 1 strongly indicating that the marine depositional environment prevailed dur- ing deposition of these samples. The tricy- clic terpane ratios for the Laverne-State-I samples suggests the Morrow in Harper County was deposited in a more terrestrial environment. The abnormally high C 19 / C 23 and C 20 /C 23 ratios (average of 2.17 and 2.88; respectively) when combined with very low C 23 /C 30 values (ave. 0.05) sug-

gest that the terrestrial higher plants were a major source of organic matter. In the Kephart-I core, fluctuations in C 19 /C 23 and C 20 /C 23 tricyclic terpane and C 23 tricyclic terpane/C 30 hopane ratios suggests these sediments were deposited in a transitional/ nearshore environment with periodic con- tributions from higher plants. A C 26 /C 25 ratio > 1 indicates possible la- custrine source rocks and/or hypersalinity (Peters et al., 2005) while C 26 /C 25 < 1 can be interpreted as possible marine source rocks with moderate or low paleosalinity of the depositional environment (Schief- elbein et al., 1999; Volk et al., 2005). The C 26 tricyclic terpane was more abundant than the C 25 tricyclic terpane in the MOR- 57, MOR-75 and MOR-91 samples, pro- posed by Schiefelbein et al. (1999) to be diagnostically characteristic of lacustrine facies. According to the depositional envi- ronment classification of Tao et al. (2015) based on the C 26 /C 25 ratio, MOR-57 and MOR-75 could have been deposited in a

Page 74 | Volume 71 Number 2

Table 3. Important biomarker parameters for isoprenoids, tricyclic terpanes, and hopanes for Morrow source rock samples

March ~ April 2020 | Page 75

Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale InThe Anadarko Basin Of Oklahoma, cont. Oil and Gas Exploration

Figure 7. m/z 191 ion chromatogram showing the distribution of terpanes

Page 76 | Volume 71 Number 2

Table 4. m/z 191 Terpane Compound Identification shown in Fig. 7.

the ratio of the C 24 tetracyclic terpane/C 23 tricyclic terpane is also facies dependent (Clark and Philp, 1989; Liu et al., 2017) with higher values (>0.6) indicating a car- bonate tendency (Clark and Philp, 1989) and lower values (<0.6) a clastic tendency for source rocks or oils. In general, the re- sults indicate that the organic matter type and depositional environment conditions alternated frequently during the deposi- tion of the Morrow in agreement with the geological description above. Hopanes Bacterially derived hopanes (Ourisson et al., 1987) are the most abundant ter- panes in the m/z 191 chromatograms from the Morrow samples with the C 29 and C 30 17( α )H-hopanes typically domi- nant (Fig. 7 and Table 4). Although none of the Morrow samples have C 29 /C 30 17(α) hopane ratios > 1, some of them (MOR- 57, MOR-74, MOR-75) have significantly higher values than the others possibly re- lated to an increase in carbonate content or evaporitic conditions prevailing during deposition (Connan et al., 1986; Riva et al.,1988). The C 31 homohopanes are domi- nant among the extended hopanes and the C 35 homohopanes are either absent or in very low concentrations, generally indi- cating sub-oxic to oxic depositional en- vironments. In the Morrow samples from Wang (1993), the average C 31 22S/C 31 (22S+22R) ratio is 0.53 while this ratio is 0.58 in the Kephart-I Well and 0.59 for the Laverne-State-I well, both of which indi- cate these samples are in the oil window (Peters et al., 2005). The 18( α )H-trisnorhopane(Ts)/17( α )H- trisnorhopane(Tm) ratio, or Ts/Ts+Tm, provides another maturity assessment in the immature to postmature range with consistent organic facies (Waples and Machihara, 1991). In the source rock samples from Wang (1993), the average Ts/Ts+Tm ratio is 0.5 and ranges between 0.06 and 0.74 again demonstrating signifi - cant maturity variations in the Morrow. In Kephart-I well, Ts/Ts+Tm ratio shows

lacustrine environment while MOR-91 was possibly deposited in a transitional/ lagoonal depositional environment. Based on the lower C 26 /C 25 ratios and relative C 24 tetracyclic terpane concentrations in the remaining source rock samples, it was concluded most of the Morrow samples could be characterized as deposited in a marine depositional environment under low to moderate salinity. The C 23 tricyclic terpane/C 30 hopane ratio has been used to indicate marine algal source input (Chester, 1990) with C 23 / C 30 with values greater than 1 strongly indicating that a marine depositional en- vironment prevailed during deposition of these samples. The C 23 tricyclic terpane/ C 30 hopane values for MOR-39 from Canadian County, MOR-41 from Blaine

County and MOR-75 from Woodward County are 1.27, 1.08 and 0.13, respec- tively. The results show that MOR-39 and MOR-41 samples probably belonged to a transitional depositional environment with a mixed type of terrestrial and ma- rine organic matter input while MOR-75 was probably deposited in a terrestrial en- vironment. These conclusions are further supported by higher concentrations of the C 24 tetracyclic terpane, typically associ- ated with a carbonate or evaporitic depo- sitional environment (Clark and Philp, 1989; Gong et. al., 2007). The relatively higher C 24 tetracyclic terpane concentra- tion in the MOR-91 samples compared to other samples suggests that this sample was probably deposited in shallow lagoon dominated by evaporitic carbonates. The ratio of the C 22 /C 21 tricyclic terpanes and

March ~ April 2020 | Page 77

Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale InThe Anadarko Basin Of Oklahoma, cont. Oil and Gas Exploration

Figure 8. Representative m/z 191 pentacyclic terpane distribution of the Morrow sample indicating the presence of oleanane and demethylated hopanes.

only slight variations to a depth of 8545 ft. and after that shows a significant increase compared to the C 31 22S/(22S+22R) ratio for the two deepest samples. The increas- ing trend in the Ts/Ts+Tm plot may be re- lated to a sudden increase in maturity but is more likely related to facies changes given the fact that the Morrow was depos- ited under highly variable, dynamic con- ditions leading to different facies associa - tions throughout the core. The m/z 191 chromatograms are also characterized by relatively high concen- trations of 18( α )H-30-norneohopanes and 17( α )H-diahopanes. The origin and geochemical significance of the 17( α )H- diahopanes is still disputed (Yang et al.,

2016) but the most consistent interpreta- tion is that the 17( α )H-diahopanes are de- rived from rearrangement of hopanoids in clay rich environments under oxic condi- tions during diagenesis (Moldowan et al., 1991; Yang et al., 2016). Anoxic condi - tions are the least favorable, while suboxic environments and brackish waters are the most favorable depositional conditions for their occurrence (Jiang et al., 2018). 17( α ) H-Diahopane is more stable than 18 (α ) H-30-norneohopane and 17( α )H-hopane and increasing maturity typically results in an increase of the 17( α )H-diahopane/ (17( α )H-diahopane+17( α )H-hopane) ra- tio (Horstad et al.,1990; Kolaczkowska et al., 1990; Moldowan et al., 1991). The relatively high abundance of rearranged

hopanes demonstrates that the Morrow was deposited under clay-rich hypersaline suboxic conditions. MOR-75 is the only sample with no 18( α )H-30-norneohopane and has the highest C 29 hopane concentra- tion which may be related to abundancy of carbonate content or evaporitic conditions during deposition. Demethylated hopanes occur as a series of C 26 – C 34 hopanes that structurally dif- fer from the hopanes by the absence of methyl group at the A/B ring (Rullköt- ter and Wendisch, 1982; Volkman et al., 1983). Demethylated hopanes are thought to form from bacterial transformation of hopanes and are often associated with heavy biodegradation of oils (Volkman et

Page 78 | Volume 71 Number 2

Figure 9. Partial fragmentogram of the m/z 217 showing sterane distribution

al., 1983) but their presence in rock ex- tracts is somewhat more unusual (Noble et al., 1985). This study confirms the ten - tative presence of demethylated hopanes, dominated by 25,28,30-trisnorhopane (TNH), 25,30-bisnorhopane (BNH) and 25-norhopane (25-NHP), in multiple source rock samples (Fig. 8). Noble et al. (1985) identified 25,28,30 TNH, 25,30- BNH and 25-NHP in Australian shales but noted the demethylated hopanes are al- lochthonous and suggested their presence was related to either paleo-seepage of a heavily biodegraded oil or biodegradation of in-situ petroleum that might have been trapped in the fractures of the shales dur- ing migration. Since these compounds are abundant in biodegraded oils, their presence in the Morrow rocks could be related to sedi- mentary re-working. For instance, heavily biodegraded hydrocarbons such as tar- sands or asphalt deposits from an ancient

reservoir could have been transported and entered the Morrow source rocks at the time of deposition (Noble et al., 1985). Alternatively, oil could have migrated from an ancient reservoir and become trapped in fractures of the Morrow source rocks and biodegraded in-situ (Noble et al., 1985). Finally, as Peters et al. (2005) suggested, their presence could be also related to a very uncommon bacterial re- working of the organic matter. Oleanane One of the most interesting features of the m/z 191 chromatograms was the presence of 18 α (H)-oleanane in several Morrow samples (Fig. 8; Table 4). Oleanane is a pentacyclic triterpenoid typically associ- ated with angiosperms (Udo and Ekweo- zor, 1990: Armstroff et al., 2006) that evolved and flourished in the early Cre - taceous Period, leading to the extensive use of oleanane as an age-specific bio -

marker for Cretaceous and younger rocks and oils (Riva et al., 1988; Moldowan et al., 1994). The depositional conditions play an important role in the preservation of oleanane (Al-Ameri et al., 2010) with hypersaline conditions minimizing the diagenetic alteration of oleanane. Fresh- water conditions prompt the degradation and aromatization of the oleanane (Mc- Caffrey et al., 1994; Murray et al., 1997a; Al-Ameri et al., 2010). Murray et al. (1997a and b) suggested that deltaic en- vironments, influenced by marine waters during early diagenesis, provide the best conditions for preservation of oleanane and other related compounds. The presence of 18 α (H)-oleanane in pre- Cretaceous source rock samples is un- usual but other studies have confirmed the presence of 18 α (H)-oleanane in pre-Cre- taceous rocks. Wood (2017) recently con- firmed the tentative presence of 18 α (H)- oleanane in the Chesterian Limestone in

March ~ April 2020 | Page 79

Oil and Gas Exploration Geochemical Characterization Of The Lower Pennsylvanian Morrow Shale InThe Anadarko Basin Of Oklahoma, cont.

Table 5. Sterane compound identification in the m/z 217 chromatogram shown in Fig. 9.

the Anadarko Basin in his unpublished MS thesis. 18 α (H)-Oleanane was identi- fied in Middle Jurassic marine siltstones of Tyumen Formation from West Siberia, Russia; a Pennsylvanian coal ball from Illinois, USA (Moldowan et al., 1994); a Middle Jurassic Brora coal in Scotland (Peters et al.,1999) and in Upper Perm- ian rock extracts from Guizhou Province, China (Taylor et al., 2006). These tenta- tive identifications of 18 α (H)-oleanane, even in low concentrations, clearly show that the presence of 18 α (H)-oleanane is not necessarily indisputable evidence for Cretaceous or younger aged source rocks and oils (Peters et al., 1999). The presence of 18 α (H)-oleanane was confirmed in non-angiosperm seed plant fossils of Cretaceous Bennettitales and the

Permian Gigantoptridales that share sig- nificant characteristics with angiosperms and have been suggested as a sister group or member of the angiosperms (Taylor et al., 2006). The results from Taylor et al. (2006) indicate that oleanane identified in this, and earlier, studies could have origi- nated from non-angiosperm seed plants that evolved during the Late Paleozoic, suggesting an alternative plant group as a precursor of oleanane. Alternatively, an- giosperms could have evolved from other seed plant lineages long before the Early Cretaceous (Taylor et al., 2006). Steranes Steranes are derived from sterols pro- duced by higher plants, animals, algae and occasionally prokaryotic organisms (Wa-

ples and Machihara, 1991). Huang and Meinschein (1979) developed a ternary diagram based on sterols to differentiate organic facies and depositional environ- ments and which was later extrapolated to the use of steranes from oils and source rock extracts to correlate, or differentiate, oils from similar, or different, sources. A representative sterane chromatogram is shown in Fig. 9 and peaks identified in Ta - ble 5. The ternary diagram for the Morrow shales show that the steranes plot between the estuarine to marine environment re- gion (Fig. 10; Table 5) and are character - ized by relatively high concentrations of the C 27 regular steranes compared to the C 28 and C 29 steranes. The MOR-11, MOR- 39, MOR-41 and MOR-75 samples from different areas of the basin, show a pre - dominance of C 29 steranes indicating a

Page 80 | Volume 71 Number 2

Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 48 Page 49 Page 50 Page 51 Page 52

Made with FlippingBook Publishing Software