The Feasibility of Recovering Medium to Heavy Oil Using Geopressured/Geothermal Fluids
NEGUS-DE WYS, JANE, EG&G Idaho, Inc., Idaho Falls, ID, O. E. KIMMELL, Fanion Prod. Co., G. F. HART, Louisiana State University, Baton Rouge, LA, M. M. PLUM, EG&G Idaho, Inc., Idaho Falls, ID
Thermal enhanced oil recovery using geopressured/geothermal fluids is a unique concept for recovering heavy and medium oils that are bypassed during conventional production processes. The successful implementation of this technology would provide an environmentally clean and less expensive method of thermal recovery, as opposed to the burning of crude oil or natural gas, used widely by industry at the present time.
The GPGT fluids are under high pressure in their parent reservoir and when linked to shallow reservoirs by suitable plumbing will provide a self-propelled method of heat transfer to a target reservoir existing at shallow depth. The GPGT fluids will heat the reservoir as in conventional TEOR. This will reduce the residual oil saturation and lower the viscosity of the oil so that it can be moved more easily and in greater amounts.
The method is similar to hot water flooding; thus the basic technology already exists. However, the major difference is the usually high total dissolved solids present in GPGT waters. The exact effect of the brine on the target reservoir is uncertain but may have a beneficial effect not only on viscosity and oil extraction but also on permeability and porosity. The operational and mechanical problems associated with piping the GPGT fluids into shallow reservoirs also are uncertain but probably can be readily overcome. The important point is that an enormous amount of additional domestic heavy and medium oil will be recovered, if the concept works. GPGT fluids combine the temperatures, propulsion, and technology that would be comparatively clean environmentally.
The major states from which considerable quantities of additional production is possible are California [42 Bbbls], Alaska [25 Bbbls], Arkansas, Louisiana, and Texas [6 Bbbls each], Wyoming [5 Bbbls], and 2 Bbbls in other states. The leading basins for application of the technology in the United States include the Gulf Coast basin, the San Joaquin basin, and the Los Angeles basin. Totals for these basins are 8.134 Bbbls of medium oil and 4.239 Bbbls of heavy oil.
The Alworth field of the south Texas Minando trend is proposed as a pilot site. The temperatures of the upper Wilcox GPGT fluids in this region range from 350 to 500 degrees F, with salinities in the range of 3600 to 70,000 mg/L. The pressures are from 800 to 3500 psia flowing wellhead pressure. The target reservoirs for injection of the GPGT fluids are the Jackson and Yegua sandstones of the upper Eocene Epoch. These reservoirs contain an estimated 4 million bbls of heavy OIP [18 degrees API], of which at least 1 million bbls could be recovered by TEOR. An additional 1.5 Bbbls of oil is recoverable from the 87 fields within the Minando trend.
Run of the economic model on the Alworth field suggests that it will be economic.
AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)