Katharine Lee Avary

CREATING A GEOLOGIC PLAY BOOK FOR TRENTON-BLACK RIVER APPALACHIAN BASIN EXPLORATION

The Trenton-Black River Appalachian Basin Research Consortium has made significant progress toward their goal of producing a geologic play book for the Trenton-Black River gas play. The final product will include a resource assessment model of Trenton-Black River reservoirs; possible fairways within which to concentrate further studies and seismic programs; and a model for the origin of Trenton-Black River hydrothermal dolomite reservoirs. All seismic data available to the consortium have been examined. Synthetic seismograms constructed for specific wells have enabled researchers to correlate the tops of 15 stratigraphic units determined from well logs to seismic profiles in New York, Pennsylvania, Ohio, West Virginia and Kentucky. In addition, three surfaces for the area have been depth converted, gridded and mapped. A 16-layer velocity model has been developed to help constrain time-to-depth conversions. Considerable progress was made in fault trend delineation and seismic-stratigraphic correlation within the project area. Isopach maps and a network of gamma-ray cross sections supplemented with core descriptions allowed researchers to more clearly define the architecture of the basin during Middle and Late Ordovician time, the control of basin architecture on carbonate and shale deposition and eventually, the location of reservoirs in Trenton Limestone and Black River Group carbonates. The basin architecture itself may be structurally controlled, and this fault-related structural control along platform margins influenced the formation of hydrothermal dolomite reservoirs in original limestone facies deposited in high energy environments. This resulted in productive trends along the northwest margin of the Trenton platform in Ohio. The continuation of this platform margin into New York should provide further areas with good exploration potential. The focus of the petrographic study shifted from cataloging a broad spectrum of carbonate rocks that occur in the Trenton-Black River interval to delineation of regional limestone diagenesis in the basin. A consistent basin-wide pattern of marine and burial diagenesis that resulted in relatively low porosity and permeability in the subtidal facies of these rocks has been documented across the study area. Six diagenetic stages have been recognized: four marine diagenesis stages and two burial diagenesis stages. This dominance of extensive marine and burial diagenesis yielded rocks with low reservoir potential, with the exception of fractured limestone and dolostone reservoirs. Commercial amounts of porosity, permeability and petroleum accumulation appear to be restricted to areas where secondary porosity developed in association with hydrothermal fluid flow along faults and fractures related to basement tectonics. A broad range of geochemical and fluid inclusion analyses have aided in a better understanding of the origin of the dolomites in the Trenton and Black River Groups over the study area. The results of these analyses support a hydrothermal origin for all of the various dolomite types found to date. The fluid inclusion data suggest that all of the dolomite types analyzed formed from hot saline brines. The dolomite is enriched in iron and manganese, which supports a subsurface origin for the dolomitizing brine. Strontium isotope data suggest that the fluids passed through basement rocks or immature siliciclastic rocks prior to forming the dolomites. All of these data suggest a hot, subsurface origin for the dolomites. The project database continued to be redesigned, developed and deployed. Production data are being reformatted for standard relational database management system requirements. Use of the project intranet by industry partners essentially doubled during the reporting period.

ENHANCING RESERVOIR MANAGEMENT IN THE APPALACHIAN BASIN BY IDENTIFYING TECHNICAL BARRIER AND PREFERRED PRACTICES

The Preferred Upstream Management Practices (PUMP) project, a two-year study sponsored by the United States Department of Energy (USDOE), had three primary objectives: (1) the identification of problems, problematic issues, potential solutions and preferred practices related to oil production; (2) the creation of an Appalachian Regional Council to oversee and continue this investigation beyond the end of the project; and (3) the dissemination of investigative results to the widest possible audience, primarily by means of an interactive website. Investigation and identification of oil production problems and preferred management practices began with a Problem Identification Workshop in January of 2002. Three general issues were selected by participants for discussion: Data Management; Reservoir Engineering; and Drilling Practices. At the same meeting, the concept of the creation of an oversight organization to evaluate and disseminated preferred management practices (PMPs) after the end of the project was put forth and volunteers were solicited. In-depth interviews were arranged with oil producers to gain more insight into problems and potential solutions. Project members encountered considerable reticence on the part of interviewees when it came to revealing company-specific production problems or company-specific solutions. This was the case even though interviewees were assured that all responses would be held in confidence. Nevertheless, the following production issues were identified and ranked in order of decreasing importance: Water production including brine disposal; Management of production and business data; Oil field power costs; Paraffin accumulation; Production practices including cementing. An number of secondary issues were also noted: Problems associated with Enhanced Oil Recovery (EOR) and Waterflooding; Reservoir characterization; Employee availability, training, and safety; and Sale and Purchase problems. One item was mentioned both in interviews and in the Workshop, as, perhaps, the key issue related to oil production in the Appalachian region - the price of a barrel of oil. Project members sought solutions to production problems from a number of sources. In general, the Petroleum Technology Transfer Council (PTTC) website, both regional and national, proved to be a fertile source of information. Technical issues included water production, paraffin accumulation, production practices, EOR and waterflooding were addressed in a number of SPE papers. Articles on reservoir characterization were found in both the AAPG Bulletin and in SPE papers. Project members extracted topical and keyword information from pertinent articles and websites and combined them in a database that was placed on the PUMP website. Because of difficulties finding potential members with the qualifications, interests, and flexibility of schedule to allow a long-term commitment, it was decided to implement the PMP Regional Council as a subcommittee of the Producer Advisory Group (PAG) sponsored by Appalachian Region PTTC. The advantages of this decision are that the PAG is in already in existence as a volunteer group interested in problem identification and implementation of solutions and that PAG members are unpaid, so no outside funds will be required to sustain the group. The PUMP website became active in October of 2002. The site is designed to evolve; as new information becomes available, it can be readily added to the site or the site can be modified to accommodate it. The site is interactive allowing users to search within the PUMP site, within the Appalachian Region PTTC site, or within the whole internet through the input of user-supplied key words for information on oil production problems and solutions. Since its inception in the Fall of 2002, the PUMP site has experienced a growing number of users of increasingly diverse nature and from an increasing geographic area. This indicates that the site is reaching its target audience in the Appalachian region and beyond. Following up on a commitment to technology transfer, a total of eight focused-technology workshops were sponsored by the Appalachian Region PTTC center at the request of the PUMP project. Five Welltender Operations and Safety seminars were held in Kentucky, West Virginia, Ohio, and Pennsylvania. A two-day Applied Reservoir Characterization seminar and a one-day course on Paraffin, Asphaltene, and Scale problems were held in Pennsylvania. A one-day workshop on Produced Water was held in OH. In addition to workshops and the PUMP website, the project also generated several topical reports available to the public through the website and through USDOE.

Computer-Generation of a Devonian Shale Production and Potential Atlas for West Virginia: ABSTRACT

In the final phase of an Eastern Gas Shales Project (EGSP) contract with the U.S. Department of Energy, the West Virginia Geological and Economic Survey compiled an atlas of Devonian shale production and potential. By using both the surveys existing oil and gas data base and a more detailed, computerized data file created during the project, 22 maps were computer-generated for areas of western and southern West Virginia. These multicolored maps show all wells with known gas production from Devonian shales, all wells drilled to the shales that were dry holes, and all other unsuccessful shale wells that produce either from shallower Mississippian or Pennsylvanian units, or from deeper units below the shales (e.g., the Middle and Lower Devonian Huntersville and Oriskany For ations or the Upper Silurian Newburg sand). In addition, a gray screen pattern on the maps indicates wells from which shows of gas were reported from the shales, and isopotential lines contour initial open flows from the shale gas wells. Thus, the atlas can be used to locate further shale wells in areas with known high productivity, as well as areas with potential for dual completions in one or more zones in addition to the shale. This atlas is one of many products that can be generated from high quality, detailed computer files. End_of_Article - Last_Page 1173------------