This paper seeks to address the challenges of BHA dysfunctions in complex wells’ environment which impacted the drilling performance in Abu Dhabi Offshore. Drilling operations experienced various cases of BHA failures, which triggered the need for advanced tools to enhance the bit and BHA design analysis during the well preparation phase. Market research was conducted to identify the commercially available software for bit and BHA design analysis. It is to enable a systematic in-house analysis of the bit and BHA proposed by the service providers to ensure the directional drilling and performance goals can be achieved. A specific drilling software was identified as a fit-for-purpose solution. It offers 3D mechanical modelling of any directional system, sensitivity analysis on multiple BHA settings, hole characteristics, and operational parameters driven by a fast-numerical methodology. The acquired software package includes several key modules: BHA pre/post-analysis, PDC bit model, local doglegs, and vibration analysis. The plan was then put in place to enable implementation across fields. In-house training was conducted to introduce the software to end users. Data gathering for PDC bit and RSS modelling was conducted in collaboration with the service providers. The BHA pre-analysis workflow was then defined to enable comprehensive bit and BHA modelling analysis, covering directional drilling analysis and vibration modal analysis. An agreed BHA configuration and stabilization was identified, and boundaries of optimized operational parameters were determined. Drilling operation was then executed with the agreed bit and BHA following the recommended operating parameters. In after, the BHA post-analysis was conducted to calibrate the PDC bit and RSS modelling by utilizing real-time data and directional drilling information. It also captured the lessons learned for bit and BHA design future improvements. The workflow was implemented for 22 drilling BHA in 2021 with most of the focus in 6″ hole section, long lateral drain application. The BHA performance evaluation of the 6″ hole section demonstrated the improvement result, with 10 out of 12 BHA achieving the objective to complete the section in 1 run. The BHA specific polar plot and RPM driller roadmap provided in this analysis functions as a practical guide for BHA analysis during well preparation and execution.

This paper aim to identify potential for improving the process of gathering trajectory directional survey data, recalculating of current wellbore position based on new information by automating the process, performing collision avoidance analysis scanning and providing feedback by using machine recognition of risk while minimizing human interaction with the dataset. The envisioned result was seen as a system where wellbore survey data would flow seamlessly from acquisition at rig site into company directional survey calculation system, where programming would use the dataset to update the definitive survey listing, update forward planned surveys, run collision avoidance scan on updated planned surveys against identified offset wellbores and verify current position in relation to plan and possible deviation to same based on company policies for survey and collision avoidance and produce output for end user(s). The project outcome was a software that acts as an intermediate between field data set repository and company directional survey software package. When data set becomes available in repository, a 30-second interval repeating query recognizes the change and updated directional survey data is moved to correct wellbore, used in defining trajectory and original plan is modified allowing collision avoidance verification to run based on new wellbore survey information. The project outcome also included machine review of the collision avoidance results based on programmed company policy values, which added to the process. The project saw substantial time delay during creation due to issues identified in the challenges part below but is now running full time for company covering all offshore rigs and associated wellbore surveying activities. Learnings during the execution of the project showed both short comings of current systems, inconsistent API (Application Programming Interface) support for legacy software, and several opportunities for further improvements to the originally identified goal and potential for creating an advisory system based on current policies, further reducing the sometimes-arbitrary decision making which can result from large variation in experience levels related to understanding risk associated with directional surveying and directional drilling.

The trial of a turbine powered Motorized Reaming Shoe (MRS) was conducted on two fields offshore Abu Dhabi involving the running of 9-5/8″ casing to planned depths in long intermediate sections. The trials involved running casing in the longest12-1/4″ sections to date on each field. This paper will elaborate on detailed parameters, Motorized Reaming Shoe features and operating practices recorded while reaming through multiple restrictions with a cumulative length of more than 200 ft, across various formations, successfully running casing to the planned depth. It will also elaborate on casing cementing and shoe-track drilling operations where MRS were deployed. Referring to the average NPT duration of similar incidents, this initiative has saved 6 to 7 days of operation (eliminating requirement to pull the casing, perform a wiper trip, and re-run back the casing). This is estimated at an average of approximately 1M$ cost savings per NPT event. The failure to run casing to section TD with the MRS in one of the trial jobs is also analyzed including detailed operational learnings and design changes that could positively impact running long casing strings in complex wells. This paper details the technical features and potential benefits of Turbine Powered Reaming Systems, how the trials were conducted and their impact on de-risking casing deployments, with specific reference to application in long intermediate casing sections offshore Abu Dhabi.

The paper seeks to address the challenges of drilling BHA dysfunction which impacted the drilling performance in Abu Dhabi Offshore. Drilling operations experience vibration and stick-slip which limited the ROP and often led to BHA failure cases. In addition, challenging trip out and casing running were observed which indicated unsatisfactory borehole quality. Enhancement of the drilling BHA is required to reduce vibration and improve borehole quality. In reference to study of Self-Excited Stick-Slip Oscillations of Drag Bits by Thomas Richard in 2001, reducing the amplitude of the vertical oscillations should lessen (if not eliminate) the severity of the coupling between the two modes of vibrations, and therefore, of the self-excited vibrations. This could be achieved by minimizing the upward motion of the BHA, by appropriately increasing the lateral friction between the BHA and the borehole wall. Appropriately means "without affecting too strongly the overall efficiency of the system." Friction Adjustable Stabiliser Technology (FAST) is designed with patented features to achieve the above-mentioned BHA condition. A series of runs with FAST incorporated into RSS drilling BHA were planned. A set of KPIs were put in place to evaluate BHA performance. The drilling BHA was simulated to obtain the optimum tool placement, in collaboration with BHA providers. The drilling results were then analysed and compared with analogue wells to demonstrate the deployment of this technology. The deployment of FAST was conducted in 12-¼″ and 6″ hole sections with a total of 7 runs. FAST was run with various RSS systems with low level of vibration in the majority of the runs and proven to minimize vibration/stick-slip during drilling by acting as the BHA contact point and delivering consistent and sufficient friction. As a result, the drilling BHAs were able to deliver the objective to TD and avoid additional trips due to BHA failure. Borehole quality was evaluated through trip out BHA and casing/tubing RIH performance. There is still room for improvement in trip out performance, as backreaming was still required in most of the runs. However, positive impact to performance of RIH casing or lower completion from good quality borehole drilled by BHA with FAST was confirmed from all runs. The saving from fit-for-purpose BHA design on average is 2 days, considering the average NPT for trip out the BHA. In addition, improvement in trip out performance in 6″ section is 0.4 days. Considering above, total saving from 6″ section is 2.4 rig days. The detailed BHA performance analysis and operation feedback from subsequent wells will be beneficial to assess the suitability of this technology to overcome future drilling challenges.