Challenging Operation in Block A South - How to Enhance Development Success in Abnormal Pressure
- Y. Wasawat (PTT Exploration and Production Co., Ltd.) | S. Sittichod (PTT Exploration and Production Co., Ltd.)
- Document ID
- International Petroleum Technology Conference
- International Petroleum Technology Conference, 14-16 November, Bangkok, Thailand
- Publication Date
- Document Type
- Conference Paper
- 2016. International Petroleum Technology Conference
- 2 Well completion, 1.7.5 Well Control, 3 Production and Well Operations, 1.7 Pressure Management, 1.2.7 Geosteering / reservoir navigation, 2.10 Well Integrity, 1.6 Drilling Operations, 2.2 Installation and Completion Operations
- Well Design, Optimization, Abnormal Pressure
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Due to highly abnormal pore pressure observed in Block A South phase I development, several unexpected problems were encountered. Well targeting, operation and integrity issues were studied to minimize in the next phase of Block A South development. Phase II well designs were renewed to gain reservoir optimization. This paper presents the field mitigation and operational improvement of Block A South development from phase I to II, and the proposed guideline to later Block A South phases. For instance, Block A South phase III is another achievement to perform on these development strategies.
Block A South comprises many reservoir sections from shallow target – 2E unit, down to deep target – FM1. Pore pressure starts to ramp up at lower 2D unit and back to normal pressure at lower 2A unit. All targets were combined in a single well for reservoir maximization in phase I. However, it caused problems in terms of well operation and integrity during production. Therefore, new well design was planned to segregate reservoir targets as shallow, intermediate and deep sections to minimize operational issues. These three types of new well designs were also incorporated with pressure pregnant profiles. After two batches of fifteen wells drilled in Platform A, many operation issues, well control, borehole collapse and well integrity, were experienced. Average well cost was approximately 30 percent in excess of plan. Only half of drilled wells cannot be put on stream as planned due to cementing and integrity problems.
For Block A South phase II, pressure prediction is precisely conscious to avoid operational problems. Platform H was first developed with abnormal pressure of 1.65 sg. The new designs show success in the platform development. The Platform H new well drilling gives rise to about 20% increase in success rate from Platform A drilling. Also, average well cost is as planned. Platform G, which investigates maximum observed pressure up to 1.85 sg, exhibited all methods to avoid operational problems. 85% of wells drilled in Platform G have no problems and average well cost is within 5 percent exceeding plan. Actual operation cost and time yield better results than expected. Additionally, larger amount of volume in Platform G has been produced comparing to Platform A. The overall result of Platform G is favorable to the next phase of Block A South development.
The strategies are acceptable results to control operation with abnormal pressure. It is beneficial to Block A South development and investment. Lesson learned from these practices will provide operational improvement in later Block A South phase. These designs can be applied to other fields in the Gulf of Thailand.
|File Size||16 MB||Number of Pages||15|