Levine, Jeffrey R.1, Creties Jenkins1
(1) Consultant Geologist, Richardson, TX
(2) DeGolyer and MacNaughton, Dallas, TX
ABSTRACT: What is the Role of the Geologist in Assessment of Continuous-Type Gas Accumulations?
Successful exploitation of continuous gas resources requires the simultaneous development of efficient, effective engineering technology together with appropriate geological data and models, which are needed to guide exploration and optimize production. In conventional gas systems, reservoirs are localized features, having more-or-less discrete boundaries. Continuous gas accumulations, in contrast, are regional in extent and lack obvious seals or traps, presenting a somewhat different set of issues. Reservoir characteristics controlling production rates and gas-in-place are inherently variable and difficult to predict. This can lead to the erroneous conclusion that geology is either too simple or too erratic to warrant investigation. Therefore, many projects have been slanted heavily toward engineering, with geology relegated to a minimal role. Many unconventional gas projects are only marginally economic, however, and cannot sustain the high cost of “exploring with the drill bit” to find economic production “fairways”. Therefore, geological issues must be fully understood, and the role of the geologist appropriately redefined.
The legitimate role of the geologist includes: helping to reducing “risk” by anticipating trends in reservoir quality; providing data for optimizing drilling and completion, remediation of production-related problems, reservoir simulation, and economic modeling; accurately assessing the distribution of gas-in-place, and improving the accuracy of reserve estimates, targeting stratigraphic intervals for completion or re-completion, determining optimal well-spacing; and providing insights to guide project expansion and acquisition. Multidisciplinary acquisition of stratigraphic, structural, hydrological, and geochemical data is required to accomplish this goal. Understanding and characterizing sedimentary organic matter is critical for sorbed gas reservoirs.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.