Tight Sandstone Reservoir Waterflooding Efficiency Study

Abstract

PetroKazakhstan Kumkol Resources JSC (PKKR JSC) has a number of assets, one of which is the RP oilfield. It has been operated without reservoir pressure maintenance. Reservoir is made of tight sandstone with permeability getting as low as 1 md. In addition, reservoir is isolated from all sides by impermeable barriers such as faults and pinchouts. There is no aquifer or gas cap detected in the reservoir. The natural recovery mechanism for this reservoir is solution gas drive. As a result of the field depletion the pressure has decreased threefold in just a few years. Hence, there is a clear need for the pressure support to stop the decline in production. Waterflooding is considered a reasonable option. However, the following questions have to be answered first: is it possible at all to inject required quantities of water in the tight sandstones with such low permeability? If it is, how much will the company benefit in incremental oil production which has to be further analyzed from economic standpoint? To find the answers to these essential questions a joint team of reservoir engineers from PKKR JSC and Schlumberger used a workflow specifically designed for this goal, which harvests the benefits of the two common industry approaches: the speed of the fast-screening with analytical methods and the level of details provided by 3D simulation model. It is important to note that one of the success criteria of this project is to automate as many steps as possible to make the workflow easy to implement for other fields. In order to minimize the risks associated with various uncertainties, sensitivity analysis and optimization techniques were deployed. As a result of this study, quick yet detailed analysis of the waterflooding efficiency including best water injection candidate selection was performed. The developed workflow can be successfully applied to other assets of the company and extended for the specifics of each field streamlining the decision-making process.

Effect of Well Orientation on Oil Recovery from Waterflooding in Shallow Green Reservoirs: A Case Study from Central Africa

“…Despite the volume of published literature [26][27][28][29][30][31][32][33][34][35][36][37][38] on the recovery efficiencies of different well types, to the best of our knowledge, there has been no research on the performance of highly deviated wells in the highly heterogeneous shallow reservoirs of the Central African Rift Valley region, which are significantly different from most moderate-depth to deep reservoirs in other parts of world. This is because of (i) the complications associated with drilling along a precise path within an inclined path, (ii) difficulties encountered in preventing sand influx, and (iii) challenges encountered during screen installation for sand production control, which render directional drilling more difficult and time-consuming for complex reservoirs.…”