HP/HT gas wells, especially those in South Sumatra, Indonesia, present many challenges to exploitation operations due to a 408°F bottomhole temperature, a 10,500psi bottom hole pressure at some 11,000ft, and sour gas components of 34% CO2 and 100 –200ppm H2S. During the final stages of the completion of one such well, after setting the production packer a wireline run was made with .108″ slick line to recover the plug body from the seating nipple at 11.406ft. While pulling out and with the plug at 6000ft. the well became live without warning, blowing the tool string up the hole and, to contain the well, the drilling BOPs were closed shearing the landing joint which in turn closed the sub surface safety valve. Subsequently the well was successfully completed and prepared for wireline fishing operations. The wireline fishing operation went on for several days using .108″ wire, during which 45 runs were made with the recovery of only approximately 550ft of wire and so it was decided to call in heavy duty wireline fishing (HDWF) expertise to review the situation and make recommendations as to how to proceed. This resulted in a commitment being made to mobilize personnel and equipment from Aberdeen and the Middle East to carry out the required operations. In the meantime a total of 11 further runs were made in the well using coiled tubing which resulted in recovery of the upper part of the tool string and some additional wire. Fishing operations were recommenced using 7/32″ Supa 75 braided cable with two two/man crews providing 24 hour operation and a project leader located at the clients office to provide for direct liaison. After a total of 17 runs over 6 days of continuous operation, the fish was completely recovered and the well made ready for production. In this paper the authors will review the situation that was faced, the remedial work done to complete the well, the early fishing operations and the subsequent input of HDWF expertise. They will conclude with a detailed account of the successful HDWF operation – an excellent example of how careful planning, experienced personnel, dedicated project management and a collaborative relationship between the client and service company can lead to a successful outcome.

From the effect of global energy demands, many oil industries are forced to search for hydrocarbons in more challenging environments. For example, drilling under high pressure-high temperature (HPHT) conditions has become common practice over the past 15 years, and new technologies are being developed to keep up with the need to drill safely and efficiently, minimize formation damage, and improve the production rate. The decision to drill two highly deviated and horizontal gas wells in the "S" field located in South Sumatera, Indonesia led to a detailed drilling strategy for managing the HPHT - sour gas environment and the narrow pressure window. Subsurface simulation confirmed that these well designs will provide additional gas recovery compared to existing vertical wells and also extend the plateau time production accordingly. The main challenge was to connect two vertical wells into one horizontal that would contribute to 60% of gas recovery from this structure. Managed pressure drilling (MPD) was the main option for drilling this well in terms of drilling risk, compared to conventional techniques. The MPD method provides better control over formation damage along the horizontal section. Stimulating deep, hot, sour gas wells can be risky, and the chance of gas recovery is less when conventional drilling practices are used. Therefore, MPD coupled with the constant bottomhole pressure (CBHP) technique was chosen to fulfill the technical requirements. The initial well production test result shows that the MPD technique succeeded in minimizing drilling-related problems along with minimizing formation skin damage. This allowed the well to meet the proposed production rate targeted by the subsurface team. This paper describes the planning process for designing MPD HPHT drilling in a sour environment well and includes the implementation results and lessons learned from the drilling process.

HP/HT gas wells, especially those in South Sumatra, Indonesia, present many challenges to exploitation operations due to a 408°F bottomhole temperature, a 10,500psi bottom hole pressure at some 11,000ft, and sour gas components of 34% CO2 and 100 – 200ppm H2S. During the final stages of the completion of one such well, after setting the production packer a wireline run was made with .108″ slick line to recover the plug body from the seating nipple at 11.406ft. While pulling out and with the plug at 6000ft. the well became live without warning, blowing the tool string up the hole and, to contain the well, the drilling BOPs were closed shearing the landing joint which in turn closed the sub surface safety valve. Subsequently the well was successfully completed and prepared for wireline fishing operations. The wireline fishing operation went on for several days using .108″ wire, during which 45 runs were made with the recovery of only approximately 550ft of wire and so it was decided to call in heavy duty wireline fishing (HDWF) expertise to review the situation and make recommendations as to how to proceed. This resulted in a commitment being made to mobilize personnel and equipment from Aberdeen and the Middle East to carry out the required operations. In the meantime a total of 11 further runs were made in the well using coiled tubing which resulted in recovery of the upper part of the tool string and some additional wire. Fishing operations were recommenced using 7/32″ Supa 75 braided cable with two two/man crews providing 24 hour operation and a project leader located at the clients office to provide for direct liaison. After a total of 17 runs over 6 days of continuous operation, the fish was completely recovered and the well made ready for production. In this paper the authors will review the situation that was faced, the remedial work done to complete the well, the early fishing operations and the subsequent input of HDWF expertise. They will conclude with a detailed account of the successful HDWF operation – an excellent example of how careful planning, experienced personnel, dedicated project management and a collaborative relationship between the client and service company can lead to a successful outcome.

A Gunung Kembang drilling campaign recently drilled three wells with 1,510-, 525-, and 283-ft MD horizontal section lengths. The landing point of these wells is 3,200 ft TVD in limestone formations. Failures from the first and third wells resulted from a total-loss circulation problem, and drilling was stopped following an uncontrolled loss rate and a diesel-oil stock shortage. Two suspected factors are believed to be the cause of loss circulation in Gunung Kembang: 1) depleted formation pressure, which recorded 6.8 ppg and led to a narrow margin of overbalance mud weight and minimum stability mud weight, and 2) the presence of natural fractures. This factor requires further discussion owing to the geomechanic study results, which predicted several azimuths that natural fractures will most likely encounter while drilling. Water-based mud then becomes an option for drilling a 6-in. horizontal section in the Baturaja limestone formation, as water supply is almost unlimited and is easy to acquire. A non-damaging fluid in combination with a glass-bubble lightweight additive is proposed for drilling this section to 1,600 ft MD. To minimize the possibility of loss circulation, mud density is designed to be slightly higher than the formation pressure. The formation pressure is recorded at 6.8 ppg, thus the mud weight will be 6.9–7.1 ppg (17–50-psi overbalance) using glass bubbles (hollow-glass spheres). A laboratory test regarding this mud system was conducted to determine the optimum concentration of glass bubbles in waterbased mud using the value of PV so as to affect ECD and surface circulating equipment reliability. A return permeability test was also conducted against the Baturaja limestone core sample with a 15% reduction in permeability. This result offers a better solution for the Gunung Kembang drilling campaign owing to its lower operational cost and that it is more environmental friendly.