Field development of mature fields in Kuwait Oil Company have seen a paradigm shift over the past couple of years, to adopt the latest field proven technology to exploit the remaining reserves. The Mauddad formation in the Bahrah field is a low permeability with high viscosity oil which was previously developed with vertical cased and perforated wells with electrical submersible pumps (ESP). Inflow monitoring also posed a challenge to conduct production logs due to challenges with the Y-tool of the ESP. In light of these challenges, it was decided to drill horizontal wells, installed with multi-stage frac completions with acid being the stimulant. The described solution was considered a recent success because of the 300% increased production compared to offset vertical wells over the same producing period. However, ESPs are still required to lift fluids to surface in these horizontal wells and the understanding of inflow performance of each stage remained a monitoring challenge. A solution was identified to utilise intelligent inflow tracers after the successful pilot in another field development in Kuwait, using passive inflow control devices (ICD) with ESPs. Therefore, it was decided to pilot the same technology which provided intervention free, permanent downhole monitoring. However, the additional challenge was to prove that inflow tracers could survive the harsh acid operation and continue to function as a reliable downhole sensor thereafter. The wells installed with intelligent chemical inflow tracers are used to provide a trend assessment of the clean-up phase of production, productivity assessment information for each stage and to event monitoring such as identifying the location of water breakthrough. Fluid samples collected from the surface flow lines were analyzed for unique chemical tracer signatures and interpreted the corresponding tracer signals. The monitoring campaigns have provided an improved understanding of fracture efficiency which has translated to frac design optimsation and also reduced subsurface uncertainty. This paper discusses the chemical sensor design, integration of the sensors, run in hole procedure, sampling, analysis and interpretations of multi-stage acid frac wells, penetrating the Mauddud reservoir. Several wells were installed with chemical sensors adjacent to the sliding sleeves compartmentalized with swell packers in horizontal producing sections of up to 3,000-ft. The post operation interpretation revealed that chemical sensors functioned after the acid jobs and revealed how each stage performed from the frac clean up operation and how productivity changed over the life of the well.

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.