This paper discusses the multidisciplinary challenges faced while assessing and developing a thin sandstone reservoir with limited connectivity and no aquifer support, and how gathered data and surveillance, combined with tests and engineering sense, turned this reservoir into a feasible development, unlocking its full potential that was overseen earlier. A case study is presented with the Lessons learned to be replicated. The reservoir in question will be referred to as IRS.

Picking and identifying the reservoir on openhole logs is difficult, as it has been overseen in the past. Few existing wells where logs are available have been re-assessed and IRS perforated and tested, yielding very positive results. Few dedicated horizontal wells were drilled with encouraging results, core has been acquired, and preparation for a water injection pilot is undergoing to close the loop with the pressure support story. All results are presented as a case study in this paper

While targeting the main reservoirs in a development drilling for the field in question, a smaller opportunity (IRS reservoir) was identified in the buildup section of hundreds of horizontal wells. The immature IRS represents the upper most part of a main sand body. The sand is enclosed between the Upper and Lower major Shale layer. It is believed that it was formed at the latest stage of Glacial age when a large lake has formed and it was receiving sand influxes from surrounding highs due to ice melt forming what is called IRS in this paper. The Cretaceous marine Shale reservoir on top acts as a regional seal and lies on a regionally extensive unconformity. The IRS reservoir is laterally discontinuous and variable in thickness and rely on truncation underneath the cretaceous Shale as trapping mechanism. The attractiveness is the stable dry oil production combined with stable pressure drop. Preliminary encouraging production data of oil per well as compared to a regular development well, generally with low water cuts. Following the implementation of appraisal and study plan, supplemented by production tests and surveillance, more confidence is being built in IRS as a feasible development reservoir, with further assessment being carried out at the time of preparing this paper.

Active development of IRS reservoir have been the attention of the authors for an extended period of time, the team of integrated disciplines has captured the development challenges from Geology, Petrophysics, Reservoir Engineering and Well Completion in a detailed manner with a clear path towards full exploitation of the reservoir. The authors trust their experience and approaches used are practices worth replicating and are captured in this paper.

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