Interpretation of a CO2/N2 Injection Field Test in a Moderately Fractured Carbonate Reservoir

Abstract

L. Denoyelle, SPE, Inst. Fran<;:ais du Petrole C. Bardon, SPE, Inst. Fran<;:ais du Petrole E. Couve de Murville, SPE, Petrorep Summary. The Coulommes-Vaucourtois field operated by Petrorep and located in the Paris basin is near abandonment. During the 25-year production span, one-fourth of the original oil in place (OOlP) has been produced by a strong bottomwater drive. Reservoir engineering studies and laboratory measurements have shown that the reservoir characteristics were favorable for CO 2 injection.In 1983, an injection well was drilled between four existing production wells. During the spring and summer of 1984, 49 x 10 6 scf [1.4 x 10 6 std m 3 ] of CO 2 followed by 54 x 10 6 scf [1.5 x 10 6 std m 3 ] of N2 were injected. After 21/2 months of CO 2 injection, gas broke through into a well located far outside the pattern area. Shortly afterward, a producing well of the pattern showed a four-fold oil production increase as gas broke through. The three other wells exhibited smoother responses, with production of minute quantities of gas. Significant WOR decreases and oil production increases were observed. Gas analyses showed that the areal extent of the gas "bubble" was 15 to 20 times larger than the pattern area and that CO 2 and N2 did not spread in the same directions.This paper tries to match the test results with the geologic description, which shows the presence of fissures, and the production history of the reservoir, which exhibits a single-porosity behavior. It also stresses the difference between the incremental oil recovery resulting from the formation of an oil bank and that resulting from the gas-lift effect.

Computational fluid dynamic simulation of multi-phase flow in fractured porous media during water-alternating-gas injection process

“…This complexity makes the design of EOR techniques difficult due to poor control of fluid injection into the system, resulting in low sweep efficiency and early breakthrough (Elfeel et al, 2016). Early breakthrough is among all possible problems observed in several case studies, indicating very low overall hydrocarbon recovery in fractured reservoirs (Davidson and Snowdon, 1978;Denoyelle et al, 1988;Panda et al, 2009). In addition, the lack of interconnected fracture networks in NFR systems makes the application of any conventional EOR technique less feasible (Dehghan et al, 2012).…”

A Unified Framework for Flow Simulation in Fractured Reservoirs

“…Enhanced oil recovery (EOR) techniques are typically used to economically extract hydrocarbons from fractured reservoirs. These techniques often rely on injection cycles of aqueous and gaseous fluids to exploit capillary and gravitational forces to sweep oil and gas toward the production wells [7,10,37] (see Chapter 7 for EOR simulations using the MATLAB Reservoir Simulation Toolbox [MRST]). The presence of fractures can lead to a series of undesired operational problems, such as the early breakthrough of injected fluids, that can severely impact hydrocarbon production and the economics of the project [45].…”