The Mauddud Formation in the Greater Burgan field is a thin carbonate reservoir with very low permeability but with moderate to good porosity and variable fracture density. The formation could be divided into three distinctive layers, based on the structural and digenetic complexities. Production in Mauddud wells show rapid decline due to tight rock matrix (low permeability). This decline is associated with an increase in Gas-Oil Ratio (GOR) as reservoir pressure falls below the bubble point pressure near the wellbore. Horizontal wells were drilled in an attempt to develop the Mauddud Formation targeting sweet zone. Most of the wells were located in a relative structural high on the up-thrown blocks of the North and Eastern flank of the Greater Burgan field that had the highest likelihood of intersecting fractures. They are mostly adjoining the major faults. There are now around 40 wells drilled in Mauddud including horizontal and multilaterals, most of which became non-producers due to above reasons. A study has been carried out to evaluate opportunities to revive these wells through available and new technologies in the industry. A detailed geological study incorporating all the available data was carried out initially. Wells were screened for stimulation by using various proven new technologies. Acid Frac, Stage Frac, near well bore SurgiFrac and Matrix Acid techniques have been applied with varying results. Advanced placement technique like distributed temperature profiling was used in some of the jobs. This paper presents the details of the application of the above mentioned technologies, to the candidate wells and discusses the results. The success of some of these technologies opened up new opportunities for a new beginning to revive the closed wells completed in Mauddud Formation.

As part of KOC strategy to develop the technical skills of the new recruits this paper will present a series of best practices related to decision workflows during drilling of horizontal wells through a recognized multidisciplinary team which optimized the preparation level and knowledge standard for the young generation through practical workshop and in short period. The best practices identified included aspects related to reservoir management, location selection, subsurface characterization and drilling specifics. Those were the key elements in the preparation of the technical training with the support of a multidisciplinary team that proved beneficial to the decision processes and issues faced during drilling in real time workflows. However optimization of a well needs skill, knowledge, right vision and experience, hence the results of the extensive drilling campaign and different cases of horizontal wells allowed the establishment of a practical training workshop protocol using actual acquired data for the planning, follow-up and assessment of drilling operations, which is now used in Fields Development South and East Kuwait. The practical workshop encompassed two case histories of horizontal wells where good decision procedure resulted in avoiding complications during drilling and effectively optimized most of the drilling path. This practical, interactive workshop was successful in developing with an integrated framework, the necessary skills in the participants, in all technical disciplines involved, namely Geosciences, Petroleum Engineering and Reservoir Engineering, in a pioneer effort of the Greater Burgan teams, not used before in KOC for training. The impact of this workshop was to enhance the experience of the young professionals in Petroleum Engineering, Geoscience interpretation and Reservoir Management, as well as to build their integrated knowledge on horizontal drilling for the benefit of KOC, across all Directorates and possibly applicable to other oil companies.

The Barremian-Aptian, Kharaib Formation is among the main reservoir units in the Middle-East. The Kharaib Formation is broadly divisible into three main zones: the Upper, Middle and Lower Kharaib, which are defined based on their distinct sedimentological characteristics. The Kharaib interval has been extensively studied across the region; however, the inherent heterogeneity associated with sediments always makes it challenging for interpretation of the depositional facies, stratal geometries, and the prediction of their reservoir properties. This study focuses on the Middle and Upper Kharaib by integrating sedimentological, diagenetic, and pore-scale datasets to provide a better understanding of the depositional framework, diagenesis and its effects on the reservoir properties. Dunham/Embry & Klovan classification (1971) scheme is used to describe the sediments, which determines lithofacies. Lithofacies that are genetically relatable are grouped into larger sets of associations. The lithofacies association represent their sedimentary environments of deposition. The grouping/stacking pattern of the sediments reflects a broad third-order sequence. Higher-order variations/sequences are either from localized topographical changes or energy variations or from sea-level changes, which thereby imparts lateral reservoir heterogeneity. X-ray diffraction (XRD) analysis defines the mineralogical composition, whereas pore-scale fabric/textural characteristics have been defined via conventional light microscopy and scanning electron microscopy (SEM). Sedimentological description of the Kharaib Formation showed varying textures ranging from mudstone to grain-rich floatstone, which are interpreted to be deposited in a broad homoclinal ramp setting. Petrographic evaluation of the sediments from the studied section highlighted the effects of diagenesis on reservoir properties with calcite cementation significantly reducing the reservoir quality (i.e., lower porosity and permeability). In contrast considerable micro and macropore enhancement due to secondary dissolution appears to negate the effects of cementation. In the studied sediments, the porosity comprises considerable abundance of primary and secondary macropores. The measured porosity varies from moderate to very good, while permeability is low to moderately high. Interrogation of conventional core analysis data establishes that the primary control on reservoir quality distribution is sediment texture and composition. The genetically distinct characteristics of lithofacies related to allochem assemblage, their abundance and size aid in defining the associations, which thereby provides the former fabric for the subsequent diagenetic alterations. The abundance of detrital clays in the middle Kharaib appears to be the primary cause of relatively poor reservoir quality. This study shows that both the original depositional texture/composition and diagenesis have had an important impact on shaping reservoir properties. This integrated approach sheds light on the sedimentological make-up, depositional setting, and diagenetic overprint of the Kharaib Formation and their effect on the reservoir quality of various lithofacies. This understanding will further develop work related to pattern prediction of the Kharaib Formation, which may be extrapolated to uncored intervals for reservoir quality correlation and assessment.

The Greater Burgan Field is the oldest producing oil field of Kuwait. Till date, more than 1200 wells have been drilled in the field. Construction of surface production facilities, power line corridors, roads as well as office and housing complexes for its employees have put severe constraints on surface locations for drilling new wells. A fault block in the Ahmadi ridge that was expected to be geologically very prospective for hydrocarbon accumulation could not be accessed for a long time as it was below the Kuwait Oil Company's office complexes. Structural complexity and poor quality of seismic data around that area also added to the uncertainty. To reach the producing Wara and Burgan sands, the wells have to be drilled through the carbonate Dammam, Radhuma and Tayarat formations which are potential loss zones – more often than not leading to total mud loss. Deviated wells drilled so far in the field were, therefore, restricted to a maximum inclination of 45 degrees with the kick-off point located as deep as possible to minimize losses. This put a severe constraint on the horizontal drift achieved at pay zone level. Two high-angle deviated wells were successfully planned and drilled with inclinations of 50 degrees or more with shallow kick-off depths to achieve a horizontal drift of upto 1 km to reach the hydrocarbons locked up below the company office complexes. The higher inclinations also helped in maximizing the reservoir contact and net pay of more than 100 ft was encountered in both the wells.

The Greater Burgan Field in Kuwait consists of three culminations – Burgan Dome in the south, Ahmadi in the northeast and Magwa in the northwest. The Cretaceous Burgan Formation is the main reservoir of the Greater Burgan Field. The major part of the reservoir consists of massive, stacked, fluvial channels with an active bottom water drive. The structure is dissected by a number of faults resulting in compartmentalization of the reservoir. The major faults are easily mappable with seismic data. However, mapping the minor faults is a challenge due to velocity anomalies present in the shallow formations masking the structural picture at the Burgan Formation level. Hydrocarbon saturation logs are widely used in the field to monitor the movement of the oil-water contact (OWC). At many places, uneven OWC rise is observed, that cannot be attributed to different offtakes from the wells. Time-lapse mapping of the OWC by different vintages of hydrocarbon saturation logs, in combination with open hole logs, shows that these differences can only be explained by sub-compartmentalization along structural discontinuities. Such discontinuities are mostly observed in the Magwa area where shallow velocity anomalies are also more pronounced. Mapping the trends of these discontinuities shows that they are aligned to the regional fault trends mapped seismically. Using this technique, a number of minor faults can be mapped that sub-divides the major compartments into smaller ones. This will help in better positioning of in-fill locations and also in refining the production strategy of the compartments.