Enhanced Oil Recovery at Zero Cost. Will Cyclic Waterflooding Breath a New Life into Mature Oil Fields? A Case Study in South Kazakhstan

Abstract

Abstract South Kazakhstan is one of the hydrocarbon rich provinces in Kazakhstan, which is among the top 20 oil producing nations. However, most of the big fields of the basin are entering the last stages of development. Consequently, operators look for opportunities to maintain economical production by applying IOR methods at lower costs. Hence, cyclic waterflooding was considered a good candidate because of no expenditures. The paper demonstrates the main stages, mechanisms, and results of the project. The schematic of cyclic waterflooding is carried out by changing injection rates in phases. This leads to fluid flows redistribution in heterogeneous reservoirs due to capillary forces. So, the field trial was implemented on the KK field, which is represented by stratified sandstone mostly waterflooded. The injection pattern is irregular and eight patterns participated in the project. Rates varied from 50 t/d up to 300 t/d. Phases consisted of one group of injectors introducing water at lower and another group at higher rates with one-month duration. After that, the wells’ rates were adjusted. Cyclic waterflooding has been in operation for almost a year. During that period, producers’ working modes haven't been changed. As the result of observations, some wells have moderate or even no impact, but some wells exhibited remarkable improvements, e.g. a producer which has three injection wells around experienced watercut decrease from 90% up to 40%, while oil rate increase from 1 t/d up to 5 t/d. Overall, oil production from a group of nearby producers whose oil rates were previously reducing with a 41% decline has a clear trend of full stabilization. The main aspect causing this phenomenon is watercut decrease. The parameter fell from 95% to nearly 86%. Thus, it became beneficial not only in terms of oil production but also surface infrastructure. Less water volume treatment is required and it is critical for gathering system under conditions of growing water production. Summing up all the above-mentioned cyclic waterflooding has big success in our field case study. The initial modest forecast turned to significant oil increment and watercut decrease. Moreover, the company saved money which makes this IOR approach the most preferable to implement. Therefore, additional two projects recently started on other similar fields. It is obvious that if properly managed, improved oil recovery is possible at no cost breathing new life into old fields.