One of a Kind BHA Design for ERD Wells in Bahrain

Abstract

An innovative BHA was designed to fit slim extended reach wellbore profiles. Precise BHA design was essential to reach the bottom of the well with a scrapper and circulate to clean the hole efficiently for enabling fracking operations with Plug & Perf technology to be performed in extended reach horizontal wells in Bahrain. Plug & Perf operations for multistage fracking required to run plugs through a cased extended horizontal section with an internal diameter of 4" to isolate the different stages to be stimulated. The max OD of the plug was 3.625 in leaving a marginal clearance between the plug and the casing, making hole cleaning the primary risk to deal with. For hole cleaning it was important to design the slim BHA with a maximum OD of 3.125 in and ensure reaching bottom. Torque & drag simulations were run using Extended Reach Architect software specialized for drilling ERD wells. This innovative use of the program required creating a fictional section in the well schematic where the new BHA design was simulated. During the execution phase, the simulations proved their accuracy while pointing out the depths where the string weight is lost, and a change in pipe diameter and weight is crucial to continue running in hole. This unconventional BHA design met not only the technical requirements, but also the logistics challenges coming from the current working pipe inventory. The team looked for alternatives by designing several BHA scenarios, changing the position, amount, weight, and diameter of pipes to be used. Innovation and accurately applied well engineering created a BHA design process that unlocked the possibility to perform the completion operations of ERD horizontal wells. Ultimately 6 ERD wells were successfully prepared for fracking operations. The implementation of this BHA design workflow decreased the number of clean out runs from 5 attempts to 1 successful run in every well, therefore reducing the operational time by 12 days per well, in overall saving 75 days. Helping to bring oil production faster in Bahrain.