A Novel Efficient Solution to Isolate Cross Communicating Reservoirs and Delay Water Advance without Impacting Well's Workover/Drilling Duration: Case Studies from Giant Offshore Field in Abu Dhabi

摘要

Facing a well control issue while drilling multi reservoirs with different reservoir pressure is very common in oil field worldwide, each and every engineer who is involved in the operations is dealing with this issue on daily basis. However, if the unexpected high pressure is observed while drilling a matured reservoir with known pressure, it is always a challenge to identify the source of the problem and to define the efficient remedial action plan, without compromising the well deliverables. The case study presented in this paper is related to a workover of a well in a giant offshore field in Abu Dhabi, where abnormally high pressure encountered while drilling the reservoir section with little amount of flow into the wellbore. Identifying the source of discrepancy and to establish the mitigate plan without impacting Well's Workover/Drilling duration was a serious challenge. What made the situation more complicated was the high risk of water in the heel section of 6" horizontal drain, which was prone to shorten the well life significantly. This paper will introduce an efficient novel solution to use 4 1/2" casing liner in a certain configuration, consisting of the mechanical and the Swellable packers to cure the cross communicating reservoirs (source of abnormal high pressure); and isolate the risky heel section of the well, to extend well life without impacting the planned well duration. This work will also describe the process of identifying the source of pressure, selecting the most suitable well completion strategy to meet the well objectives successfully. Moreover, it will also shed some light on the need of using reservoir simulation technique to assess different well completion options. Finally, the paper will be concluded with methodology on how to save time and cost whilst changing plans to cope with the unforeseen issues.