EOR Feasibility for Mexico's Mature Fields

Abstract

Abstract Within the Mexico energy reform, a static and dynamic characterization was made from two representative sectors from the mature fields bidded on the R1-L03 to evaluate the implementation potential for EOR. Two reservoirs were studied using public and generic information in each of them:A naturally fractured carbonate reservoir, dual porosity (matrix/fracture), with tight porosity (6.3%) and permeability in the matrix and high permeability in the fracture. Clean Carbonate with low clay content, average depth: 3400 [m], fluid type is a gas and condensate with retrograde condensation (49.7 °API), with an underlining regional aquifer as the primary drive mechanism.The model is populated by 5 wells with a combined 2670 [m3/d] maximum production of oil and 3766140 [m3/d] of gas. This production declined to 16 [m3/d] of oil and 70800 [m3/d] of gas. The initial pressure of 376 [bar] being declined about 30% 279 [bar]. The model also contains a numerical aquifer.A shaly sandstone sequence reservoir highly laminated, containing high porosity (20%) and high permeability. Unconsolidated sandstone with average depth of 320 [m], the fluid is heavy oil of 20 °API, The reservoir is mainly discontinuous having poor or none vertically communication, arealy there are evidences of communication. The reservoir drive is mainly volumetric with no evidence of aquifer support.A sectorial model which contains 12 wells is used, this reservoir had produced for 46 years. The maximum production reached 825 [m3/d] of oil, currently the oil production is under 95 [m3/d]. In both models a history matching was made representative for pressure and production, then it was simulated a production forecast of 15 years with natural depletion and enhanced oil recovery implementation. They were modeled through numerical simulation evaluating different enhanced oil recovery processes, both miscible injection (natural gas, N2, CO2, hydrocarbon gas injections) and thermal recovery (cyclic steam, continuous steam injection, SAGD and HASD); these methods were selected trough compatibility criteria for every case studied. Miscible gas injection was simulated in the naturally fractured reservoir, the additional recovery factor achieved lies between 0.4 and 1.6%. With economic analysis this recovery factor might result in economic unviability, on the other hand according to simulation results a higher recovery factor and profitability could be reached with natural depletion adding drilling new wells and major workovers to the actual ones. The thermal EOR methods were simulated in a sandstone reservoir containing heavy oil, in this reservoir a 0.7 to 4.2 % additional recovery factor was achieved and this indicates technical feasibility in the implementation of this kind of processes.