Publications

Because of the mature age of the Foxtrot Field, it has become imperative to undertake various innovations and technological advancements in oil and gas activities in this field. All the concepts are geared towards obtaining efficiency and significant cost optimization for the entire exploration and production activities.

Two unconventional architectures called Light Architecture (LA) and Extended Light Architecture (ELA) have been designed and implemented in Foxtrot to simplify the conventional drilling concept. Both architectures consist of the 20” CP, 9-5/8” surface casing, and the 3-1/2” tubing which also acts as a production casing. The ELA is for a reservoir zone two times larger than the LA. The surface casing depth was set at 1400–1800 mTVD for both designs, considering an 8m^3 kick margin. The study in this paper seeks to optimize the determination of the shallowest surface casing depth that can be set while considering the economics and the safety procedures of the entire fit-for-purpose drilling activity. The idea is to shorten the depth of the surface casing by maximizing the kick margin at 3m^3 and having the Equivalent Circulation Density (ECD) at a value lower than the fracture gradient at the optimized shoe. The study was conducted based on the kick margin calculations approach and the result was corrected using the “StressCheck” Landmark.

The results of the study highlighted the high potential of shorter surface casing setting depths for any upcoming LA/ELA wells to be designed at an optimized casing setting depth of 800–1200 mMD. The optimization will bring savings from the casing cost, the rig cost for casing installation, and the mud volume cost at the surface section of up to 200,000 USD per well, with an average of 116,000 USD per well, contributing to the continued drilling improvements in the Mahakam Delta.