Wireline Formation Tester surveys are routinely performed for pressure profiling in all new wells. These surveys are being extensively used to identify contacts, cross communication etc. The information is updated and integrated for a full field perspective so that depletion trends, communication across faults, and presence of sub-layers within the main sand lobes are identified, validated and mapped. This data set is acquired over time, against a well laid out strategy and against all the sands.As a precursor for building a model in a multilayered mature oil field of Kuwait, the collected data were analyzed to draw interesting and operationally important conclusions.The study reinforced the sub-layering classification followed in the field on a broader scale; however in a few instances, marked anomalies were noted. The existing sand layering scheme was revisited and corrections applied by adjusting the layer tops in those wells.Multiple pressure points across adjacent sub-layers with close pressure regime were grouped and re-grouped and plots were generated. The layers followed the existing geological layering scheme; but in some instances, the plots indicated a different picture of the extent of these sub-layers. This type of validation of layering scheme of the static model gave important insights during upscaling for the dynamic model. Analyses of the plots were carried out in different segments for well clusters across faults. The plots uncovered important information about the nature of the faults. Conclusions drawn from these plots are planned to be used for supplementing Pressure Transient Analysis information during history match.

Natural dumpflood injection is used for pressure maintenance in a good channel sand holding considerable reserves. The layer is on depletion drive with very weak aquifer support. Natural dumpflood injection was modeled based on success in a similar layer in an adjacent field. Due to the high mud weight used during drilling, the layer is usually damaged. Dumpflooding experience in the analogue field suggests that injection is initiated only after matrix acid stimulation. Therefore, it was not a surprise when the layer did not take in any water initially. However, once the usual stimulation attempts did not achieve the desired results, possible causes and alternates were evaluated. A comprehensive lab study was designed to assess all the potential problems associated with injection. Fluid-fluid interaction issues like scaling, possible formation of oil-in-water emulsion, fluid-rock interaction such as clay swelling, fine migration related to water incompatibility, all impacting efficiency of water injection on oil mobility and recovery were studied. To simulate every possible field condition all the major water sources were sampled and taken for study. For fluid rock interaction studies, core plugs from the layer was used. Scale tendency was studied using Jar test and predictions at reservoir conditions were made through ChemScale software. The scaling products from Jar test was analyzed with SEM confirming the results. Routine core analysis was performed to measure porosity and permeability in the coreplugs. XRD was done to understand the mineralogy of the layer. After measuring the baseline permeability, the plugs were subjected to flooding with source waters. One set of coreplugs were fully saturated with target water and flooded with source waters. Flooding was repeated on core plugs saturated with oil at irreducible water saturation until it reached residual oil saturation. An investigation of emulsion formation was conducted between oil and source waters. Study results gave an indication of many potential issues like self scaling tendency of source waters and permeability reduction due to fine migration and scale formation. Out of the many factors, the presence of considerable concentrations of sulphate forming cations was identified as the primary issue to focus on. Sulphate reducing chemicals are being evaluated for injection along with the source water. Injection water quality is one of the primary factors to consider for effective injection. This is even more crucial in case of dumpflooding, wherein water is sourced from sub-surface. Due to the wide extent of the field and possible diagenesis effect there could be regional variations in water quality. Due diligence needs to be paid to these regional variations in water quality and choose prudently among alternate source water reservoirs.

Reservoir Depletion is addressed in many ways across the globe with water injection being the most common method. A typical full field water injection scheme takes years for implementation, with surface players like injection facility construction dominating the project cycle and delays are not uncommon. The resulting loss in deferred production and recovery along with continuous amendments to production profiles of the field can be minimized by resorting to DumpFlooding as an easy and quick alternate.ЉAЉ field is a satellite field of Kuwait. Bulk of production is from the thin estuarine channel sand of average thickness of 13ft within Zubair Formation. This channel system is laterally continuous as interpreted from the Isopach map and has a fairly uniform pressure throughout the field. With no aquifer support, a decrease in pressure from the initial levels of 2500 psi by around 1000 psi was observed. The production performance also deteriorated since the operational teams had difficulty keeping the ESPs on operation continuously. The size and location of the field could not economically justify a conventional water injection project. As the reservoir pressure came perilously close to the bubble point, a partial pressure maintenance scheme was conceptualized, with DumpFlooding as injection mechanism.A systematic plan to address all the uncertainties that could have an impact on the success of the project was listed and addressed. The injection volumes and injection patterns were evaluated and firmed up by a simulation study. Various source water reservoirs were identified and water compatibility analysis was carried out to confirm the suitable injection water. Multiple single well pilots with completions from different source water reservoirs were tested. The productivity & injectivity indices of the different sources and the sink were ascertained. When the full field implementation was carried out, the team was able to take further steps with considerable confidence, having taken important lessons from each stage.The concept proved to be successful with real benefits seen on the ground. The layer saw a gradual rise in reservoir pressure monitored by an intensive surveillance programme. A rise in pump intake pressure of ESPs ranging between 150 to 200 psi within a span of 1 year was noticed. The field started experiencing trouble free ESP operation. New horizontal producers drilled as a part of the scheme resulted in significant oil gain. A 25% increase in overall layer production was observed. The paper discusses the key milestones from conception to implementation with emphasis on the role played by each stage in the grand scheme of things. A case is thus made for considering DumpFlooding as a necessary intermediary in any upcoming water injection project.