Fibrous LCM Sweeps Enhance Hole Cleaning and ROP on Extended Reach Well in Abu Dhabi

Abstract

Abstract Extended reach wells pose some unique problems to the drilling operation in the management of hole cleaning and torque and drag. Cleaning the hole without inducing an excessive equivalent circulating density (ECD), resulting in down-hole losses, can be a major issue when drilling extended reach wells. The reduced mud weight / fracture gradient window can limit pump rate making it difficult to achieve adequate solids transport, particularly in long 12 1/4" tangent sections. Experience on world record extended reach drilling (ERD) operations led to the discovery that certain fibrous lost circulation materials (LCM) have the ability to enhance hole cleaning and dramatically reduce torque and drag in high angle and horizontal well-bores, as well as control losses. Optimised drilling practices, together with the application of engineered hole cleaning sweeps, can greatly improve drilling efficiency in extended reach wells. This paper focuses on the successful application of fibrous LCM sweeps on the first extended reach well to be drilled in Abu Dhabi by the Abu Dhabi Company for Onshore Oil Operations (ADCO). In response to difficulties sliding in 12 1/4" hole, hole cleaning sweeps were routinely pumped from 9,462 feet, in the 63 degree tangent section, to final TD in 8 1/2" hole at 17,525 feet. Coupled with pipe rotation, these sweeps increased the rate of cuttings return to surface by up to 50% and frequently resulted in major improvements in the drilling rate. The effectiveness of these sweeps was monitored on surface at the shakers by visual means and downhole by means of annular pressure monitoring tools in the bottom hole assembly.