Simulation Case Study of Water Shut-off With RPM Gels in an Oil Field in Northern Germany

Abstract

Abstract Relative Permeability Modifying (RPM) gels are cross-linked polymers which reduce the water and oil relative permeability disproportionately and reduce the water production from a single well. RPM gels are the preferred choice for water shut-off when a well with no zonal isolation is producing from multiple layers among which, no cross-flow exists and at least one layer is producing relatively dry oil. In these conditions application of RPM gels limits the water production until water block or rarely gel desorption ends the favorable effect of the RPM gels. In this study, a black oil reservoir in north of Germany is screened to examine the feasibility of RPM gels water shut-off treatment. This homogeneous reservoir has been under production for the past 25 years and is heavily water-flooded from early years of production due to its weak drive mechanism. The reservoir is producing with an average of 75 % water-cut and requires urgent water shut-off solutions. In this paper the screening process with additional focus on the simulation stage of the screening process is described in details. The reason for the additional focus on the simulation part is lack of documented studies on simulation aspect of such projects which has led to non- negligible problems in simulating such treatments. Once the reservoir is screened considering the petro physical properties of the rocks surrounding the production wells, a water shut-off index is defined for each of the production wells which takes into account the necessity of the well for treatment as well as the risks involved by the quality of the simulation model. Based on the water shut-off index the most promising well is chosen and 3 cycles of RPM gel injection in this well is simulated. Several scenarios are defined to find out the optimum gel volume based on the incremental oil production. The best scenario resulted in 1.54 Million bbl of field incremental oil compared to the "do nothing scenario" in a period of 8 years, performing 3 consecutive gel injections. It is tried to present a detailed work-flow for screening and appraisal of such projects for the similar reservoir and operational conditions.