Slimhole completions have been applied worldwide for years. The aim of this type of completion is to reduce well costs (drilling and completion) and therefore improve project economics. This paper presents the results of applying slimhole completions into oil and gas wells in the Offshore North West Java (ONWJ) Field, Indonesia. In looking back at the performances of previous wells, this paper focuses on problems associated with slimhole wells during completion time and their post-production compared with potential cost savings and future well intervention benefits.
To date, more than 40 slimhole wells have been drilled in ONWJ fields. Typically, the wells were completed in 3-1/2" or 2-7/8" monobore. Cost savings were achieved through these completions. However, additional problems seem to have arisen during completion time that could reduce the economics of the project. The most frequent problem during completion was due to cement obstruction (22.2% from total cemented wells) in the liner section after the cementing job, caused by poor cement displacement. This commonly occurred on relatively deep and deviated wells. From previous experience, drilling practice has improved, resulting in fewer operational problems during completion time.
The overall results show the problems associated with slimhole are still within an acceptable range compared with the potential cost savings and benefits. In our case, production rates from slimhole-monobore wells have not been much different from conventional wells. This paper also shares some operational practice improvements made to reduce problems associated with slimhole-monobore wells.