Print this pageNovel Chemical EOR Processes for Improved Oil Recovery from Fractured Reservoirs
Many reservoirs from which oil is produced are not homogeneous in the geologic properties (e.g. porosity and permeability). In fact, many of such reservoirs, especially those consisting of carbonate type of rocks (e.g. limestone and dolomite) are naturally and significantly fractured. Typical examples of such reservoirs are those in the Spraberry trend in West Texas.
Two new chemical EOR processes are available for field deployment that can be economic even at oil prices that are $20/bbl or less, and of course have very attractive economics in the current high oil price environment. In addition, both of these EOR methods may be performed on an individual well basis, and hence can be applied and optimized at a low cost in a short time before initiating larger projects. When applied correctly, both of these chemical EOR methods require only a few dollars of chemical cost for each incremental barrel of oil recovered.
One of these processes is surfactant EOR in fractured carbonate reservoirs. Customized chemical formulations can be applied at producers in a soaking process to stimulate recovery of oil normally trapped in the rock matrix. The added chemical allows the water-phase to penetrate into the matrix and not just move within the fracture system. The same formulation may be added to the injection water to treat an entire pattern of the reservoir.
A second new low cost EOR method is using Pre-formed Particle Gel (PPG) for improved conformance control. Suspensions of particles swell in the injection water will plug preferentially high permeability watered-out channels. Subsequent injection water will be forced into previously unswept tighter zones and recover additional oil. The PPG technology is decided advantages over current so-called bulk gel technology.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil