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Field Evaluation of the Caney Shale as an Emerging Unconventional Play, Southern Oklahoma
Project Number
DE-FE0031776
Last Reviewed Dated
Goal

The overall goal of this project is to establish the Caney Shale Field Laboratory in southern Oklahoma to conduct a comprehensive field characterization and to validate cost-effective technologies that will lead to a comprehensive development plan for the Caney Shale, characterized by high clay content and ductile behavior. 

Performer(s)

Oklahoma State University, College of Engineering, Stillwater, OK
Oklahoma State University, Geology, Stillwater, OK
Oklahoma Geological Survey, Norman, OK
Lawrence Berkeley National Laboratory, Berkeley, CA
University of Pittsburgh, Pittsburgh, PA
Continental Resources Inc. Oklahoma City, OK

Background
Caney shale field lab

The Caney Shale is an emerging unconventional resource play in the southern mid-continent Anadarko, Ardmore, and Arkoma basins. The Caney reservoir is approximately 60–300 m thick, rich in total organic carbon, contains a large oil resource platform, and has a strong natural gas drive. However, development has been hampered by high clay content and reactivity of the formation with water.

The first phase of the project (years 1 and 2) will focus on studying the Caney shale. The second phase of the project (years 3 and 4) will focus on field development, starting with a horizontal well being drilled in Caney.

The project’s first objective is development of an open, collaborative, and integrated program to comprehensively characterize the geological, petrophysical, and geochemical properties of the Caney Shale and its reservoir fluids. The geomechanical properties of clay-rich ductile shale are not known and can contribute to the know-how for fracturing such formations.

Secondly, the project aims to gain a fundamental understanding of hydraulic fracture initiation/propagation, fracture and proppant permeability, proppant embedment, and fluid-rock interaction in the Caney Shale using laboratory data, field observations, and modelling.

Finally, the project will validate the findings and recommendations from the first phase of the project by drilling, stimulating, and testing a horizontal well. Based on the results from this study, a development plan and best practices manual will be developed for the Caney Shale in southern Oklahoma. This will facilitate accelerated development of not only the Caney Shale play but also help develop understanding of ductile shale fracturing and exploration of upcoming unconventional resources.

Impact

Because this is an emerging play, the project intends to contribute to the fundamental understanding of Ductile Shales for applications in hydraulic fracturing; subsurface storage; carbon capture, utilization, and storage/enhanced oil recovery; and potential contribution of shales to well “plug and abandon,” ultimately allowing the team to safely, economically, and responsibly produce Caney Shale.

Accomplishments (most recent listed first)

OSU Geology TASK 4a: Jim Puckette

  • Mapped reservoir units in the vicinity of the Tomaney core and used the kerogen-corrected variable density equation to bring as received density porosity values in line with those from tight rock analysis. Facies mineralogy will be examined next to assess the relationship between facies and selected log curves to improve interpretation of facies based on log curve response.

OSU Geology TASK 4b: Mike Grammer and Yulun Wang

  • Conducted a preliminary interpretation of stratigraphic framework and potential reservoir distribution by tying detailed core description with log response of the Tomaney well. This framework will be extrapolated into nearby uncored wells and regional-scale mapping will be conducted to characterize the geometry of depositional system and the distribution of potential reservoir units.

OSU Geology TASK 4c: Jack Pashin

  • Continued work on structural geology and burial history. Burial and thermal models have been constructed that model maturation, hydrocarbon generation, and structural evolution. Pennsylvanian folding and thrusting has successfully been modeled and had a major effect on burial history on tectonic uplifts.

OGS TASK 4d: Abbas Seyedolali

  • Extended the detailed fault, structure, thickness mapping, and internal parasequence characterization of the Caney Shale across the Oklahoma petroleum provinces: Anadarko, Ardmore, Arkoma, Marietta basins, and Cherokee Platform.  
  • Performed on the Tomaney core the multivariate statistical analysis on the rock characteristics and clusters from the TRA and Rock-Eval pyrolysis data sets and combined them with the OGS Digital Rock Classification (DRC) characterizations. Each potential reservoir has distinct rock properties.
  • Updated the regional thermal maturity estimations of the Caney Shale in the Oklahoma basins. Potential target areas/zones defined.
  • Introduced the Pitkin Limestone/Fayetteville shale members in the eastern part of the Arkoma Basin: Caney Shale lateral facies change towards a carbonate-rich, less restricted marine environment in eastern Oklahoma. 

OSU PETE TASK 5a: Geir Hareland

  • The drilling group has determined the constants necessary for the Wynell well reservoir and has used the drilling determined USC to calculate the geomechanical log and investigated different formulations for the Stimulation Index (STIX).  The drilling cost and required drilling files for the drilling optimization have been prepared for the Wynell and the Garret wells and preliminary drilling optimization has been done to determine the optimum drilling scenario for those wells. 
  • In a meeting with CLR 3/9/21 the upcoming well plan was discussed with planned depths and equipment.  The well location and reservoir zone have been determined which will be integrated into our next quarter planning for drilling and stimulation on the upcoming well. For stimulation CLR/OSU has determined that formation stiffness is the key parameter for potential selective stimulation zones

PITT Task 5b: Andrew Bunger

  • The University of Pittsburgh team continues to conduct rock mechanics experiments to characterize strength, elastic, and creep properties for the 5 Caney zones of study. Triaxial strength testing is now complete for horizontal core plugs in all 5 zones. 
  • Creep testing is complete in one zone with a second zone in progress. Low confinement testing to simulate unconfined compressive strength at reservoir temperature is complete in one formation. All testing of horizontal core is expected to be complete within the next 4 weeks, after which the same suite of experimental will be applied to vertically oriented cores. 
  • The experiments are showing that nominally “ductile” zones are indeed weaker, but are not demonstrably less brittle when compared to nominal “reservoir” zones. 

OSU PETE Task 6a: Mileva Radonjic

  • Proppant embedment: Preliminary data obtained following API propped fracture flow protocol showed that ceramic proppant outperforms white sand. Indentation data obtained on 5 rock samples from Caney core, at different orientation to the bedding, is also completed. All samples were further investigated with the Raman spectroscopy, True Microscopy profilometry and SEM/EDS, in an effort to correlate susceptibility to proppant embedment to rocks composition/microstructure. Clay rich samples have different response to microindentation compared to carbonate/quartz rich samples. The micromechanical behavior is also influenced by bedding orientation and the presence of natural microfractures.
  • Geochemistry: Preliminary experimental data was collected Geochemical reactivity of Caney rock (crushed powder) samples in 3 different fluids at 95C for 30days, under static conditions and ambient pressure. Effluent analysis show that: Overall effluent pH changes are driven by both, HF fluids and mineralogy; Ca and Si leaching is dominated by fluid type, for all rock types and at all times; it appears KCl provides most stability for clays based on this data; SO4 leaching is dominated by mineralogy; B leaching is significantly dominated by fluid type, where for all 3 rock types KCl produces highest B concentration. Microstructural evaluation of solid particles as well as bulk XRD analysis did not provide significant difference. 
  • Compositional and microstructural analysis are in progress, as Low Vacuum FIB-SEM with BSE/EBSD/EDS has recently been acquired. In addition, XRD analysis will be repeated using spraying tool that was delivered recently. This will allow EDS/EBSD correlation and 3D characterization of Caney shale at nanoscale.
  • Flow-through experiments in propped fractures using field hydraulic fracturing fluids is in preparation, and will provide data on fracture permeability, proppant embedment and rock-fluid geochemical changes at 90C, and maximum 6000psi closing (confining) pressure. 

OSU PETE Task 6b: Prem Bikkina

  • Geochemical and petrophysical properties of Caney shale available in the existing literature are studied. A procedure is developed to functionalize microfluidic chips with Illite and illite-smectitie clays, as they are the most dominant clay minerals of Caney Shale. Implementation of the clay coating procedure on resealable flow cells is in progress. The geomaterial micromodels will be used to investigate the swelling, fines migration, and wettability alteration behavior of clay when exposed to drilling, completion and injection fluids. The interfacial properties (IFT and Contact angle) of Caney shale and fluids will be quantified using a HPHT goniometer.

LBNL Task 7 a: Jonny Rutqvist

  • Geochemical Modeling: Developed a preliminary numerical model of the batch reactor experiments conducted at OSU to investigate the geochemical interaction of Caney Shale minerals with hydraulic fracturing fluids.  Because we only had basic mineralogy data and a simplified description of the lab experimental procedures, this was a proof of concept exercise for which detailed agreement with experimental results was not expected or achieved.  The work was useful in making clear what information is required for accurate modeling, and this information will be collected both to improve the model of existing experiments and make sure future experiments use procedures that will be amenable to modeling.

LBNL Task 7b: Christine Doughty

  • Geomechanical Modeling: A journal paper related to single proppant modeling and micromechanics imaging was submitted to a journal and is currently in revision. A literature study on shale creep has resulted in the selection of the creep constitutive model that we think will be suitable for our purpose of predicting the longer term fracture closure behavior based on shorter term creep laboratory experiments. The creep constitutive model is being implemented into the numerical simulator.  

OSU PETE Task 8: Geir Hareland

  • The stimulation group has set up the GOPHER reservoir model matching fracturing pump pressure and production on the Wynell from 5 of the 32 stimulation stages performed on the well.  Different stimulation scenarios were presented and indicated that smaller spacing gave highest production and value which was presented to CLR 3/9/21. 
  • A new reservoir and geomechanical model will be developed for the planned reservoir #3 zone where a close to 90-degree horizontal well is planned as next year’s well.  Guidelines from CLR for closer spacing and a 2-mile lateral will be simulated, and different scenarios stimulation parameters will be investigated. 
Project Start
Project End
DOE Contribution

$7,790,979

Performer Contribution

Industry Contribution: $12,135,800

Contact Information

NETL – Joseph Renk – Federal Project Manager (joseph.renk@netl.doe.gov)

Oklahoma State University – Mileva Radonjic, Principal Investigator (mileva.radonjic@okstate.edu)