MAJOR OIL PLAYS IN UTAH AND VICINITY QUARTERLY TECHNICAL PROGRESS REPORT

Utah oil fields have produced over 1.2 billion barrels (191 million m). However, the 13.7 million barrels (2.2 million m) of production in 2002 was the lowest level in over 40 years and continued the steady decline that began in the mid-1980s. The Utah Geological Survey believes this trend can be reversed by providing play portfolios for the major oil-producing provinces (Paradox Basin, Uinta Basin, and thrust belt) in Utah and adjacent areas in Colorado and Wyoming. Oil plays are geographic areas with petroleum potential caused by favorable combinations of source rock, migration paths, reservoir rock characteristics, and other factors. The play portfolios will include: descriptions and maps of the major oil plays by reservoir; production and reservoir data; case-study field evaluations; locations of major oil pipelines; identification and discussion of land-use constraints; descriptions of reservoir outcrop analogs; and summaries of the state-of-the-art drilling, completion, and secondary/tertiary recovery techniques for each play. This report covers research activities for the sixth quarter of the project (January 1 through March 31, 2004). This work included analyzing best practices used in the Northern Green River Formation and Deep Overpressured plays of the Uinta Basin. In these two plays, production and ultimate recovery in the Altamont-Bluebell-Cedar Rim field trend leaves a significant amount of oil unproduced. Identifying which beds actually contribute to the production and the role that naturally occurring fractures play in the reservoir remains a major trend-development problem. Staging acid treatments over smaller (500-foot [150 m]) intervals and greatly increasing the amount of diversion material used has been shown to be effective for maximizing production. A bed-scale completion technique could be effective in older wells nearing depletion where a larger staged completion is no longer economical. Therefore, in older wells it is recommended that treatment of a few individual beds be attempted using a dual packer tool. This way, only the few beds with remaining oil potential are acidized, reducing the size of the treatment needed, and providing more effective stimulation of the beds with remaining potential. Hydrochloric acid has been, and still is, the recommended treating fluid. Good diversion is also critical to treating the entire interval and a high-enough pumping rate must be maintained to carry the diverting agent. A pumping rate between 8 and 12 bbls per minute (1.31.9 m/min) with proper gelling agents in the fluid will divert the fluid to the perforated intervals, and maintain a reasonable well-head-treating pressure. High-rate hydraulic fracture treatments should be considered on newer wells. Extended hydro-jetting may be a technique to overcome near-wellbore damage caused by drilling and treatment fluids. The dual-burst, thermal-decay time and dipole-shear anisotropy logs are reliable tools for evaluating remaining hydrocarbon potential and fracture density in a cased-hole well that has been producing oil for many years. This type of data can be used to identify potentially productive beds that are not perforated in older wells, eliminate the acidizing of previously perforated beds that have little to no potential, and determine if the acid-fracture treatment is hydraulically fracturing the formation. As part of technology transfer activities during this quarter, project team members joined Utah Stake Holders Board Members in attending the Uinta Basin Oil and Gas Collaborative Group meeting in Vernal, Utah. An abstract on basin-wide correlation of Green River Formation plays and subplays in the Uinta Basin was accepted by the American