Studies and efficiency assessment of acid treatment in subsea production wells in Dai Hung field
Abstract
After a long production period, most subsea wells in the northern area of Dai Hung field (DH-01) have been heavily damaged along with fast reduction in flow rate, low wellhead pressure and discontinuous production. To improve production and recovery, the Petrovietnam Exploration Production Corporation (PVEP)/Petrovietnam Domestic Exploration Production Operating Company Limited (PVEP POC) has carried out a series of studies to evaluate the level of formation damage and made proposal for acid treatment. However, pumping acid into producing wells is a high-risk operation and in some cases could lead to loss of wells. Additionally, the implementation of acid treatment in subsea wells is highly challenging and there has been no precedent in Vietnam. This paper reviews the efficiency of innovative improvement in acidising practices for subsea wells in Dai Hung field. The acid pumping helped treat the near-wellbore damaged zone effectively, bringing 6/8 subsea wells back to stable production with flow rate increment of 12 - 40%, and in some special cases achieving oil rate from 4 - 11 times higher (DH-12X, DH-4X, and DH-5P). The improvement in acid treatment with high success rate (about 75%) has helped maintain and enhance production efficiency, provided premises and valuable lessons for future acid operations in Dai Hung as well as other fields.
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