Rapid Planning and Execution of the First Multilateral Well in the Gulf of Thailand: Results and Lessons Learned
- Eric R. Upchurch (Chevron International E&P) | Paul A. Dooley (Chevron Corp.) | Kenneth H. Hall (Chevron Thailand E&P Ltd) | Songklod Laohaburanakit (BJ Services Intl.) | Vichai Maroongroge (Chevron Thailand E&P Ltd) | Douglas McKee (Chevron Thailand E&P Ltd) | Panaratn Nucharoen (Chevron Thailand E&P Ltd) | Michael R. Wagner (Chevron Thailand E&P Ltd)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- June 2008
- Document Type
- Journal Paper
- 100 - 111
- 2008. Society of Petroleum Engineers
- 2.2.2 Perforating, 5.6.4 Drillstem/Well Testing, 1.14 Casing and Cementing, 3 Production and Well Operations, 5.1.2 Faults and Fracture Characterisation, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 2 Well Completion, 1.6.1 Drilling Operation Management, 7.3.3 Project Management, 1.12.2 Logging While Drilling, 1.6.2 Technical Limit Drilling, 4.1.5 Processing Equipment, 7.2.1 Risk, Uncertainty and Risk Assessment, 6.1.5 Human Resources, Competence and Training, 1.10 Drilling Equipment, 2.4.3 Sand/Solids Control, 4.5 Offshore Facilities and Subsea Systems, 1.6.6 Directional Drilling, 3.1.6 Gas Lift, 1.12.1 Measurement While Drilling, 1.11 Drilling Fluids and Materials, 4.1.2 Separation and Treating, 3.3.1 Production Logging, 1.6 Drilling Operations
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In early 2006, Chevron International E&P drilled and completed the first multilateral well in the Gulf of Thailand. Routine development drilling in the Kaphong field of the Pattani basin unexpectedly discovered two production horizons that possessed reservoir characteristics and sufficient oil reserves to make each a viable horizontal-well candidate. At the time, however, only a single drilling slot was available on the platform; thus, dictating that only one wellbore could be drilled to tap both reservoirs. Further complicating the problem was that the drilling rig that discovered the horizons would be moving to a new platform 5 weeks after it was understood by reservoir engineers, geologists, and geophysicists that multiple horizontal-well candidates existed.
This paper chronicles the rapid processes that took place to evaluate, plan, and execute the first multilateral well in the Gulf of Thailand. More importantly, this paper captures the unintended consequences (both good and bad) that came with executing this project so quickly. This includes an analysis of how decision making, project planning, and ultimate execution where affected by the short time window available. From this, we discuss lessons learned that may be universally applicable when rapidly expanding the use of technology in a remote region of the world (regardless of how small that expansion is).
The Pattani basin in the Gulf of Thailand is a region containing significant oil and gas reserves. Chevron Thailand has been producing from this basin since 1981. Although predominantly a gas-producing region, the northern sector of the Pattani basin is oil-rich and has been the focus of significant development in recent years. The push for greater oil development has lead to sizeable production increases in the last 4 years. One key component to these production gains is the use of horizontal wellbores. Although only 20 standalone horizontal wells had been drilled before drilling the multilateral well discussed in this paper, they collectively contribute 11% of the 107,000 bbls/day oil production from Chevron's Gulf of Thailand operation while making up only 4% of the well count.
With the strength of their oil-rate contribution, it makes sense that Chevron Thailand would want to drill as many horizontal oil producers as geologic reality would permit. It is within this setting that Chevron Thailand unexpectedly found two pay zones atop each other ( separated by, 400 ft true vertical depth (TVD) that were both legitimate candidates for development using horizontal wells. This discovery occurred in February of 2006 while drilling a series of 20 nonhorizontal oil wells from the Kaphong Delta satellite production platform (KPWD) within the Kaphong oil field. The problem, however, at the time of this discovery is that only one of the 20 available drilling slots was still undrilled, thus forcing a difficult choice to be made. Do we stay within our currently well-defined technology-knowledge envelope and drill a single-horizontal wellbore, leaving one of the two producing horizons fallow until it can be drilled at a later date from an abandoned drilling slot? Or, do we step slightly beyond our local experience base and attempt drilling a multilateral wellbore to immediately maximize the oil-rate potential presented by these two producing horizons? Given ample time, all the necessary engineering steps for making this decision can be performed to arrive at a logical and well-defined solution. In this instance, however, time was not abundant. From the time it was understood that two economically viable horizontal-well targets existed, only 5 weeks remained before the drilling rig must either spud this well or move to another platform. This, in turn, compressed the time window for deciding how to proceed with this project to only 2 weeks, allowing the balance of time for appropriate predrill engineering and operational planning.
In the end, the first multilateral well in the Gulf of Thailand was successfully drilled, completed, and put on production—but not without its share of difficulties and missteps. Implementing a technological step forward (even if it is a small one) is never without risk. Introducing such a step into a new country or region can only add to the possible risks. But doing it in a compressed time frame (though necessary in some cases) certainly introduces the greatest risk. From project inception to final completion, the team tasked with drilling this well understood this fact. Time limits, though, demand that trade-offs be made between execution readiness and planning completeness, with some of those trade-offs being unintended. The purpose of this paper is to describe the intended and unintended trade offs that occurred, their overall impact on the project, and how they relate to the environment in which this project was conceived and implemented.
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