A big-bore, high-pressure/high-temperature (HP/HT) drilling and completion program of seven wells was undertaken under challenging conditions in a low-pressure carbonate reef in Indonesia. Significant enhancements made during the program substantially reduced well times and cost. These wells incorporated the largest tubingless gas completions in the world. Higher-than-anticipated initial flow rates were achieved through an innovative strategy to decrease formation damage. The wells were completed openhole without pumping kill-weight fluids at the end of underbalanced drilling (UBD) operations. These wells are the first to combine bigbore completions, drill-in liners, and UBD in individual wellbores.Abnormal Pressure. A significant pressure ramp begins at approximately 7,500 ft TVD in the Keutapang formation and extends

The ability to optimise the use of carbon steel in sour service presents man y economic advantages, including minimizing the use of expensive corr osion resistant alloys, enabling optimised large bore completions, and eliminating addit ional offshore facilities. An integ rated approach to corrosion modeling and testing has been d eveloped to reliably extend the ap plication of carbon steel. Key elements of this integrated approach include: (1) ri gorously establish tubular environmental conditions, (2) accurately simulate environmental conditions (acid gas concentratio ns (CO 2 /H 2 S), water c ut, and water composition) in the laboratory, (3) mathematically extrapolate laboratory weight loss and pitting to predict tubing life, and (4) validate tubing life predictions with field caliper data. This paper describes the application of the inte grated approach to evaluate L80 tu bular corrosion and predict tubing life for a range of a cid gas (CO 2 /H 2 S) concentrations. The pape r also discusses the corrosion mechanisms and validation of predicted corrosion with field caliper data.

This paper will focus on a project to redevelop a wireline deployable metal-to-metal seal, ISO 14310 VO qualified, retrievable bridge plug system to allow it to be conveyed successfully in a high rate gas well for acid stimulation zonal isolation operations. Functionality of the original system including the plug and hydrostatic setting assembly had previously been tested in a fluid environment yet envisioned for a gas well application. Initial well installations gave results that led to a reconsideration of the forces being generated by the running and pulling tools due to the differences between a gas and a fluid environment and their impact on system reliability and functionality. The paper will discuss some of the problems discovered with the system for this particular application and the system redesign over a one-year period, which included a number of qualification tests performed at near to real well conditions. This discussion will include information on the complexities of performing such tests and the solutions used to develop a successfully qualified "fit-for-purpose" redesign. The paper will conclude with a high-level overview of the system's first deployment in an actual field well application. Introduction In mid 2006, the operator ran a specifically developed high expansion, retrievable, metal-to-metal (MTM) bridge plug on three 7-in. monobore wells to provide mechanical zonal isolation for high rate, multi-stage acid treatments. The acid stimulation objectives in these three wells were fully met and the MTM seal performed to expectations; however, there were significant operational problems related to the plug system. The MTM bridge plug had been selected due to previous operational problems with conventional elastomeric element type retrievable bridge plugs as well as a number of advantages that the technology presented over these conventional types of plugs for the operator's specific application. Over the course of a year, the system was redesigned to address specific findings from those initial operations. The redesign involved modifications to the plug and the inclusion of additional components and functionality in the running and pulling tools to ensure repeatable system reliability and operability. Final system qualification was extensive and more comprehensive than normally performed for such a system. The redevelopment program and qualification testing demonstrated the importance of testing complete systems at conditions representative of those that would be encountered in actual well operations. Repeat testing was important to establishing system reliability. It also highlighted the need for a project-based approach with clear communication on a regular basis between multi-disciplinary, cross-functional teams. Completion and Reservoir Overview The operator has implemented two different types of big bore wells to deliver high flow rates. The well types are a 7-in. tubing monobore and a 9" x 7"-in. tubing optimized big bore (OBB). They are shown in Fig. 1. The reservoir formations are cased and cemented behind a 7-in. production liner in both types of well. Typical well deviations are approximately 55º. The reservoir formations have significant vertical extent and are initially over-pressured but at moderate temperature. Reservoir pressures may vary between zones and this causes cross flow between completed reservoirs. To produce at the design rates for an extended period, high volume matrix-rate-multi-stage (MRMS) acid stimulations are required. The substantial reservoir heterogeneities combined with the significant vertical extent of the productive zones present extreme challenges for acid treatments for all zones.

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fax 01-972-952-9435. AbstractA Big-Bore HTHP drilling and completion program of seven wells was undertaken under challenging conditions in a low pressure carbonate reef in Indonesia. Significant enhancements made during the program substantially reduced well times and cost. These wells incorporated the largest tubingless gas completions in the world. Higher than anticipated initial flow rates were achieved through an innovative strategy to decrease formation damage. The wells were completed open-hole without pumping kill weight fluids at the end of underbalanced drilling operations. These wells are the first to combine Big-Bore completions, drill-in liners and underbalanced drilling in individual wellbores.