PROSPECTS FOR THE APPLICATION OF COMPLEX EVALUATION OF THE IMPACT OF WELL KILLING OPERATIONS BASED ON WELL TEST DATA

To reduce the negative impact of well killing operations, numerous studies have been conducted to investigate the compatibility of formation water with well-killing fluids, selection of killing fluids, core flow characteristics, and elimination of adverse effects of well killing. Far fewer well tests aimed to assess the impact of well-killing fluids have been reported. However, well tests unlike other studies, provide a realistic picture of formation fluid movement in real reservoir conditions. In light of the above, special field well tests of production and injection wells before and after well killing without well servicing have been performed. Previous large-scale well research findings before and after simple well-servicing operations have also been re-interpreted and analyzed.Results of large-scale well research interpretation suggest that the productivity of production wells and skin factor after well killing operations remained almost unchanged, as evidenced by mean values, the median and maximum number of occurrences on the histogram. Reservoir flow properties have also remained almost intact according to special well tests of terrigenous reservoirs. The negative impact of killing fluids may possibly be eliminated over time as they are extracted from well with produced fluids. These studies are not consistent with core flood experiments.In contrast to production wells, injection wells exhibit an evident decrease in injectivity after well killing operations. This is attributable to squeezing of killing fluid farther into formation. Over time, injectivity decline becomes less pronounced and then stabilizes. For two tested injection wells, the average irreversible decrease in injectivity is estimated at approximately 12 %.