Root Cause Analysis of Loss Circulation Problem and Designing/Customizing Wellbore Strengthening Materials in One of the Middle East Oil Fields- A Case Study

In the drilling industry, one of the most important parameters to improve the drilling of new wells is studying the previously-drilled wells to find major common problems and use new methods to prevent them. This article has aim to discover the root cause of loss circulation and its consequences problems right in one of the Middle East oil fields. Also, it will be discussing customizing solutions to cure or prevent such problems. Previous problems are interpreted based on lithology, hydraulic and rheological parameters. Loss circulation volume and rheological parameters (eg gel strength) were analyzed in ۱۲ drilled wells in the specific field. Based on the results, in ۵ wells, the loss problem was severe, and the cause was the creation of induced fractures due to the high volume of gel strength. Also, using the geo-mechanical models revealed that induced fracture was expected to develop approximately ۳۶ microns through drilled formations. that the reducing gel strength is sometimes not affordable due to hole cleaning issues. Hence, it has been customized for loss prevention. Accordingly, the wellbore strengthening materials with a mean size of ۳۶ microns were proposed to increase the fracture gradient of formations pressure to drill with high-density muds. By implementing recommended materials in two new wells with high-gel strength, fluid losses, and related problems were considerably showed a reduction. Thereafter, Nonproductive time compared with previously-drilled wells was reduced between ۷۱ to ۸۹%. Also, fluid loss volume dropped from ۵۱۱ bbl to ۷۵-۱۰۰ bbl in each nominated well. Meaning an ۸۰-۸۵% reduction in fluid loss, indicating reasonable achievements.

Keywords:

Mud Loss Circulation , Drilling Problems , Drilling Fluids , Induced Fracture , Loss Preventative Material