The Late Albian Mauddud Formation of North Kuwait is composed of inner ramp carbonates and deltaic clastics. It hosts prolific hydrocarbon reserves in Kuwait and across the Arabian Gulf region where the reservoirs are typically the carbonate deposits. Accurately predicting the reservoir properties in the Mauddud Formation is challenging due to the non-unique wireline signatures, which result from the inherent diagenetic heterogeneity and complexity. 385ft of continuous FMI image log data, collected from a single well covering the entire formation in a north Kuwait field, has been analysed to assess its potential to characterise and extrapolate the sedimentological, diagenetic and reservoir characteristics into uncored wells. Nine distinct image facies have been defined, each of which display a specific image fabric. The image facies have been calibrated with core, thin section petrographic observations and core plug data to aid reservoir quality predictability. The study shows that gross sedimentological and diagenetic characteristics observed in the core, including laminations, patchily distributed cements and bioturbation are identifiable in the image logs. The image facies display mottled, laminated or massive fabrics. The argillaceous, fine-grained deltaic clastics, which are non-reservoir, correspond to the finely laminated image facies, however, these deposits are easily identified in uncored intervals by their distinct wireline log signature. The mottled image facies, which is associated with patchy calcite and dolomite cemented carbonates, are subdivided into six categories primarily based on the mottling size. This work establishes a systematic relationship between the mottling size and the grain to micrite matrix ratio of the deposits, and hence, the depositional setting. The finest mottles, corresponding to the smallest cement patches, are typically associated with micrite-supported lithofacies representing deposition in a low-energy inner ramp environment, while the coarsest mottles are principally observed in the grain-supported carbonate lithofacies, which are prevalent in higher energy inner ramp environments. This relationship, which possibly relates to differences in the bioturbation and/or diagenetic overprint of the deposits, is used as a proxy to interpret the depositional energy in the Mauddud Formation. Cross-laminated and massive image facies are also locally identified and are predominantly associated with high-energy shoal complex carbonates. The image facies, in part, also predict the distribution of some of the best porosity and permeability in this formation, notably in the finer mottled image facies where reservoir quality is good to moderate (HeΦ 12.5-25.8% and Kair 1.04-22.4mD). In the coarser mottled image facies, reservoir quality is heterogeneous, but can be comparably good. Using this approach, the gross rock and reservoir properties of the Mauddud Formation can be partly characterised using FMI data alone. The scheme will be refined using further core-calibrated FMI datasets from additional wells to ultimately aid the prediction of reservoir quality at field-scale.

Since, the discovery of the Mid-Cretaceous Mauddud formation in the Sabriyah and Rhaudhatain fields of North Kuwait, there has been an interest to systematically produce the thick (> 400 ft) carbonate-dominated section, which has a complex geological setting that influences the performance of these reservoirs. Several wells have been drilled in the past-deviated, vertical, and horizontal wells focusing solely on the carbonate-dominated reservoir section with little emphasis on the siliciclastic shoreface facies of the lower Mauddud formation.The use of state-of-the-art real-time logging-while-drilling (LWD) data from the distance-to-boundary (DTB) resistivity mapping technique coupled with normal triple combo LWD formation evaluation log measurement and real-time pressure and mobility estimations provides insight into the lateral facies changes and the heterogeneity of the MaH reservoir layer for the first time.The predominantly carbonate Mauddud formation stratigraphically overlies the greater Burgan member. It was deposited in a low-to high-energy shallow marine ramp setting. The high-energy facies at the base is punctuated with out-of-sequence siliciclastic influence marking the waning of the deltaic Burgan sand influx. The upper part of the Mauddud formation is a highly diverse suite of low-energy carbonate facies characterized by highly bioturbated and reworked massive beds of wackestone and packstone with few depositional textures. This section is overlain by the prograding clastic sediments of the Wara formation and capped by the extensive transgressive shale of the Ahmadi formation.Well A (SA-0X05), the appraisal well, was planned to cut across all the Mauddud 10 reservoir layers and go lateral into the MaH reservoir with 100% NTG, thus yielding maximum reservoir contact (MRC) to evaluate this sand body for the first time. The results from porosity measurement validated the static model for this interval, and the pressure regime and mobility where inline with predicted values considering vertical variations. Lateral facies changes were observed showing coarsening-upward, clean-grained facies towards the base and the fine-grained glauconitic facies on top. Although an approximate20-ft thickness of sand was observed as a correlatable sequence from offset wells, in reality, geosteering revealed that the lower 15 ft of section was mostly distal in origin and changed to a more marine offshore facies below.