First Trial of On-Demand Activated Axial Agitation System on Abu Dhabi Offshore Operation

Abstract

The Axial Agitation System is an effective friction reduction solution on directional motor and rotary steerable system (RSS) bottomhole assemblies (BHA). Drilling performance in a high dynamic friction environment is often limited due to high fluctuations in the drillstring’s revolution per minute (RPM) and torque, often coupled with stick/slip. This drilling dysfunction diminishes the amount of energy spent on rock shearing. The weight on bit and torque from the surface are not efficiently transmitted to the bit. If left unchecked, the rate of penetration (ROP) will be suboptimal, and stick/slip may lead to mode-coupling of vibration (lateral, axial) and BHA whirl, increasing the risk of downhole tool failures and non-productive time (NPT). The Axial Agitation System has been successfully paired with RSS drilling BHAs in ADNOC Offshore fields in 13 different wells. The first three wells were qualitatively and quantitatively studied by Gohel et al.6. Performance analysis performed on each well against a comparable offset well consistently demonstrates considerable improvements in drilling performance. While efforts have been made to select offset wells with minimal differences (well trajectory, BHA and drillstring design, formations, etc.), there is still a variety of RSS applications where the Axial Agitation System’s benefits need to be fully quantified and objectively concluded. An On-demand Axial Agitation System that can be activated—when needed—allows for a more objective comparison since the bit, BHA, drillstring components, and dynamic environment remain constant. This paper analyzes the first trial results of this on-demand axial agitation system by benchmarking the drilling performance before and after activation in two wells offshore Abu Dhabi. The data were acquired from two wells with different directional profiles and BHAs to prove that the agitation effect was equally tangible in different applications. The analysis metrics include, but are not limited to, mathematically modeled algorithms during the planning stage, surface data acquisition systems, and downhole dynamics measurements. The results of the analysis quantitatively indicate an enhancement of the drilling dynamics by more efficient use of available energy for maintaining and improving the ROP. To further enhance system performance, lessons learned are identified and discussed in this paper.