Interference testing although primitive in terms of its introduction and idea to the petroleum industry, still stands to this day as one of the most cost effective and efficient ways of establishing communication between wells and determining the reservoir transmissibility in the region. This paper discusses the methodology and results obtained from a four month pressure data acquisition campaign for a transient interference test performed in a carbonate reservoir known as Marrat, in the Giant Burgan field of Kuwait. The Marrat long term interference test was conducted around a water injector pilot with distances as far as 0.9 km at the subsurface locations between the injector and producer wells. Therefore, the interference test was used to evaluate the transmissibility between the injector and the nearby observation wells. The producer wells were shut-in for the entire length of the test so as not to create any disturbances that could hinder the interpretation processes. After conducting this test, a better understanding of the subsurface uncertainty as well as communication between the wells was highlighted. Other objectives were added to the tests which were to determine the water bank distance from the injector, as well as to describe the least resistive path that the water prefers to travel in. The tests showed that not all the wells responded to the pressure pulse, and therefore the assumption that a fault was isolating one of the wells. One of the main conclusions was a strong directional transmissibility that was at first associated with a high permeability corridor corresponding to the depositional environment. The other conclusion was the orientation of the fracture plane which could cause this high directional transmissibility. A comparison and integration of the acquired pressure data with a separate geologic stochastic model was constructed and discussed in this paper. Based on the integration work of the interference test and the geologic study it was therefore concluded that a secondary recovery using water flooding would be beneficial and necessary for sustaining Marrat reservoir production in the long term based on the location of both producer and injector wells.
The Wara reservoir is one of the four main reservoirs in the Greater Burgan field, the world's largest sandstone oil field. It has experienced significant pressure decline after 60 years of primary production. In 2005, design for a pressure maintenance project (PMP) via a peripheral waterflood was initiated to arrest pressure decline and improve oil recovery. A key building block of the Wara PMP is a stand-alone, full-field Wara simulation model. The 23-million cells geological model was scaled-up to 4 million cells for flow simulation. Four pseudo layers were added to the simulation model to allow fluid migration via faults from the lower reservoirs. The new model has 100 m x 100 m areal cells and individual layers with an average thickness of 6 ft. Overall, this new model has 18 times refinement compared to the previous model for the Wara reservoir. Thus, this model is suitable for evaluating PMP, infill drilling and pattern waterflood. This paper, however, focuses on PMP evaluation only carried out over the last four years. The final history-match has been carried out at three levels: Field, Gathering Centers (GC) and Key Wells. Detailed study of interactions among field permeability distribution, edge aquifer representation, and fault transmissibility specifications on simulation results was key in developing a meaningful history-match. PNC data for many wells around the periphery of the field provided useful insights for edge aquifer representation. Water cut match was less than satisfactory for wells located in the center due to modeling deficiency of pseudo layers as discussed in the body of the paper. Prediction runs have been set up to investigate various PMP designs. These runs include sensitivity with respect to number of injectors, number of producers, target injection rate per well, maximum bottom-hole injection pressure, voidage replacement ratio, injector-producer distances, and injector-producer rows along with various scenarios for dealing with production from existing Wara producers throughout the field. This flow simulation model will be used as an operating model to optimize process design and well location. Introduction Greater Burgan, which is located in southeastern Kuwait, covers a surface area of about 320 square miles and has been ranked as the largest clastic oil field in the world. The four main reservoir units comprising the Greater Burgan Field complex are the Wara, Mauddud, Burgan Third Sand and Burgan Fourth Sand. The Greater Burgan Field is separated into three producing areas, Burgan, Magwa and Ahmadi. No structural, geologic or reservoir features distinguish these areas, although PVT differences are assigned for areas north and south of the Graben fault. The Wara and Mauddud reservoirs are separated vertically from the remaining reservoirs by extensive carbonate and shale intervals. However, extensive faulting does allow communication between the Wara sand and the Burgan Sands. Wara reservoir has an average thickness of 160 ft and historically, 336 wells have produced from the Wara reservoir at one time or another.
Interference testing is the oldest but still the most effective way of establishing communication between wells and determining the reservoir transmissibility. However, data can be difficult to interpret and the results can be misleading. Fortunately, simple steps can be performed to validate the data and obtain first estimates of the formation parameters. We demonstrate this methodology for an interference test performed in the Greater Burgan field in Kuwait.A pilot project was started to understand how to successfully inject water in the Wara reservoir. Seven wells were drilled in an area away from the existing wells: one injector at the center of a 250 m-radius hexagon formed by six producers. An interference test was performed between the injector and the producers. The main objective of the study was to evaluate the transmissibility between wells and the permeability anisotropy in the formation. In five of the producers, the target sands were oil bearing, whereas surprisingly, the same sands were water bearing in the sixth well. Consequently, a second objective was added to the study: to check whether the sixth well was in communication with the other wells and to determine the origin of the water.The tests showed that all wells responded to the pressure pulse, including the sixth well, thus refuting the assumption that a fault was isolating it. The fall-off analysis of all the wells highlighted the presence of boundaries, a finding that was consistent with the fluvial depositional environment. Moreover, the analysis showed that the channel was narrowing near the sixth well. Therefore, we could hypothesize that the sixth well had been drilled in a zone with perched water trapped by the channel boundaries. A few weeks after the test, the oil cut started to increase in that well, confirming our hypothesis.The findings from this pilot project proved the efficiency of waterflooding as secondary recovery method and were used to design the pressure maintenance program.
Kuwait Oil Company initiatives for ushering in a new era of digital transformation of its assets to intelligently and optimally manage the Oil and Gas fields were successfully realized with the completion of three pilot projects entitled Kuwait Integrated Digital Fields (KwIDF). This paper discusses major achievements of the Digital Oilfield technology implemented in Burgan KwIDF project and provides an insight on the challenges in operating it. The Burgan KwIDF pilot successfully transformed GC-1 production asset into a fully instrumented DOF comprising of digital instruments and infrastructure installed at well site and the production facility. Real-time production data is transmitted to a state of the art collaboration center that integrates data continuously with automated workflows for validation, modeling and tuning of well and facility models. Right time decision support information generated from smart visualization tools allow quick actions for production optimization, well and facility management in a collaborative work environment. There is persistent value realization from KwIDF technology implemented in Burgan field. It has generated substantial cost savings with faster response time in restoring production and reduction in non-productive time. Driven by the digital environment asset production has sustained at target as production gain opportunities are capitalized and losses compensated quickly. Over the period of time with experience in utilizing the DOF technology it has been observed that the technology sustainment is dependent on the technology providers to a large extent. The main components that require their continuous support are the digital instruments, proprietary software, hardware and related infrastructure. Technical expertise in each domain is necessary for ensuring continuous and smooth operations in the field, wellsite and collaboration centers. Development of an integrated team of domain experts is crucial for successfully managing the DOF operations. Change management initiatives for developing an in house user champion team is mandatory for ensuring sustainment. The important lessons learned and solutions are discussed in detail.
Greater Burgan in Kuwait is the second largest field and the largest clastic reservoir in the world. Discovered in 1938, the production initially came from Wara sandstone and soon followed by other underlying Burgan clastic reservoirs. Burgan reservoir mainly consists of three reservoir units namely Wara, Third, and Fourth sand. The Wara Water Flood Pilot Project is the first clastic waterflood pilot in Kuwait. Reservoir pressure in Wara has been falling below the bubble-point in many parts of the reservoir. This would ultimately result in free gas evolving from the oil and significant loss in reserve recovery. This pilot was designed with the objective to obtain information in the areas of:Long-Term InjectivityReservoir ConnectivityWater Breakthrough Time and DirectionWater-Cut DevelopmentProductivityOperational Experience The Wara pilot pattern is of inverted seven spot with one injector, six producers, and one water source and was designed to inject 5,000 to 10,000 bwpd into a single injector and to produce from six producers drilled around the injector. Each well is 250 meters apart and the producers are equipped with ESPs to produce even after water breakthrough. The project has been in the operational phase for the last two years and the main objectives of evaluating long-term injectivity and the reservoir response to water injection in the Wara reservoir were achieved. Results from this pilot were needed to reduce subsurface uncertainty and to support the design of future Wara waterflood projects. This will ultimately help in the decision of whether to build a permanent water flood project to maintain astable reservoir pressure in the Wara reservoir. This paper highlights the challenges and accomplishments in designing, completing, and operating of this successful water flood pilot project which could benefit other similar projects around the world. 1. INTRODUCTION The Greater Burgan field is located in the South-Eastern part of Kuwait as shown below and is producing most of the oil for the state of Kuwait. The Burgan reservoir mainly consists of three reservoir units namely Wara, Third, and Fourth sand. The Third and Fourth sand members have excellent reservoir characteristics and are prolific producers. At this time the Third sand is the major producer and contributing around 60–70% of the total present production of the Greater Burgan field.
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