Application of MPD Technology for HP/HT Wells in Vietnam

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One common issue among operators in determining whether to install a managed-pressure-drilling (MPD) system for a campaign is the significant upfront cost. However, through detailed cost/benefit analysis and examination of lessons learned, it becomes clear that the benefits in operational safety, drilling optimization, and nonproductive-time reduction through the use of MPD significantly outweigh the cost. The complete paper discusses lessons learned and best practices of MPD technology in relation to high-pressure/high-temperature (HP/HT) wells drilled in Vietnam.

Preparation for MPD: Constant-Bottomhole-Pressure (CBHP) Drilling in an HP/HT Environment

HP/HT drilling activities offshore Vietnam commonly experience a narrow margin between formation pore pressure and fracture gradient, in which variation in bottomhole pressure (BHP) can increase the risk of an underbalance during static wellbore conditions and lead to a higher chance of fracturing the formation in dynamic conditions. Thus, a detailed hydraulics analysis was performed with a proprietary software to simulate several scenarios at the casing shoe, at the peak-pore-pressure point, and at the target depth of the 12¼-in.-hole section.

Formation prognosis for Well A showed a converging pore-pressure/fracture-pressure (PP/FP) window with depth; therefore, hydraulic modeling and analysis were performed by choosing the pivot point set at bit/total depth, and the loss of annular friction during pump-off events would be compensated for on the basis of selection of pressure at this point. The flow behavior during MPD-CBHP application was simulated to define the circulating parameters that will be used while drilling. These parameters will maintain the dynamic BHP within the PP/FP window, which will be evaluated as the drilling progresses by adjusting surface backpressure (SBP) through the automated MPD choke manifold.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 180637, “Best Practices and Lessons Learned on the Application of Managed-Pressure-Drilling Technology for High-Pressure/High-Temperature Wells in Vietnam,” by Bao Ta Quoc, Tan Chai Yong, Harpreet Kaur Dalgit Singh, and Vi Pham Nguyen, Weatherford, prepared for the 2016 SPE Asia Pacific Drilling Technology Conference and Exhibition, Singapore, 22–24 August. The paper has not been peer reviewed.
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Application of MPD Technology for HP/HT Wells in Vietnam

01 April 2017

Volume: 69 | Issue: 4