The Operator planned and conducted Underbalanced Coiled Tubing Drilling (UBCTD), operations on 3 wells in Operator Onshore fields targeting tight sour gas carbonate reservoirs. The objectives of these operations were to evaluate the applicability of the technology in these fields, to understand requirements and methods of the technology and to evaluate the benefits of drilling the target formations in an underbalanced mode. As a preliminary step, the Operator conducted a feasibility study that flagged potential limitations to deploying UBCTD operations in existing wells, due to limitations on the completion design and other factors. All of this resulted in the plan to drill fit-for-purpose wells to the top of the reservoir to facilitate the deployment of the technique. These wells were completed with 5.5/4.5 in. Tubing and 7 in. Liner and left with a 100ft open hole interval from where CT drilling operations would later continue. The results of the feasibility study notwithstanding, additional detailed engineering work was performed in all aspects of the design by the operations team to ensure the success of the trial, including a review and validation of the available data and the feasibility to deliver the stated objectives (lateral length, underbalanced conditions, minimal flaring operations, drilling fluid re-circulation, etc.). As a result of this approach, all three wells were successfully drilled in underbalanced conditions and to the target lateral length of 4,000 ft. Well placement was facilitated using Biosteering techniques and continuous monitoring of the well performance vs. drilled footage, allowing steering decisions to be made in real-time to maximize the production of each lateral, resulting in outstanding production results of 3x the productivity of similar wells drilled conventionally, (after stimulation). This paper will detail the design process highlighting key engineering decisions and assumptions taken during the design process and comparing them to the actual behavior of the well and the impact of real-life constraints on the operational parameters. The base design and lessons learned from the project will serve as a launching pad for planning and efficiency gains for future UBCTD operations.
Drilling fluid losses while drilling a mature cretaceous limestone reservoir unit (Formation A) has been worsening over years with reservoir depletion and lack of pressure support. New drilling methods were needed to eliminate or reduce total losses and the associated non-productive time with them. Nitrified Managed Pressure Drilling proposed to help in mitigating losses and reducing non-productive-time. This paper explains the challenge, details the solution that was proposed to tackle, and discusses the results of the application. Nitrified Managed Pressure Drilling (MPD) decreases the Equivalent Circulation Density (ECD) below the lowest possible static mud weight (water) and at the same time deals safely with any unintended hydrocarbon influxes while drilling the reservoir 6″ hole section. The well data was analysed and modelled with different Nitrogen pumping rates and Surface Back Pressure (SBP) to determine the best rates that a mitigates losses but at the same time prevent hydrocarbon influxes. A closed-Loop drilling system proposed utilizing rotating control device, a separation package, and locally produced membrane Nitrogen allowed to manage the annular hydraulic pressure profile accordingly and mitigate the total losses scenario eliminating the wait on water time Rigorous planning and disciplined execution have led to safe and successful conclusion with no QHSE issues encountered. The designed Nitrified Managed Pressure Drilling solution succeeded in preventing the drilling fluid losses in the reservoir section by reducing the overbalance pressure of the drilling mud from 700 psi to 250 psi, which resulted in the elimination of 3 days of the rig's non-productive-time related to waiting on water. The closed-loop system coupled with a precise data acquisition and monitoring system has helped in maintaining a slight overbalance condition over the reservoir preventing any unintended hydrocarbon influxes to the surface. The lessons learned captured from this operation have contributed to the optimization of the Nitrified MPD in (Formation A) and to the overall MPD implementation in ADNOC fields. This paper displays the first application of nitrified managed pressure drilling in the United Arab Emirates. The equipment design and planning have accounted for many different scenarios, as this type of drilling technology enables more precise wellbore pressure management with less interruptions to drilling ahead
This article will show how Abu Dhabi Company for Onshore Oil Operations (ADCO) Drilling Division and its contractors obtained employee commitment resulting in world class performance in HSE for the past five years and recorded the lowest Total Recordable Injury Rate (TRIR), in ADCO's Drilling Division history and the longest time without LTI (Eighteen months without LTI) in 2011. In addition we have recorded zero car related injuries for the past five years and zero spills in 2011 and 2012. DOIRC (Drilling Operations Incident Review Committee), a monthly meeting with all our contractors was a key factor in improving the safety performance of the drilling community by developing 360 0 communication between ADCO main office, ADCO field, Contractor's management office and their teams in the field .The forum also have shifted from a reactive committee where only incidents are discussed to a proactive forum where best practices are shared and a communication network was established to inform the fields on regular basis. In addition to that, DOIRC High Profile Tours (rig visits by ADCO and contractors Top Management), onsite workshops and regularly launching campaigns with our drilling contractor National Drilling Company (NDC) were the additional tools used to raise Drilling Division performance to a world class performance.ADCO Drilling Division has clearly established a successful formula for its safety performance to reach and maintain a world class performance for the past five years, reaching 0.52 TRIR in 2011and 0.60 in 2012 and 0.09 LTIF in 2008 and 2010;the lowest in ADCO Drilling history through effective communication culture.
The proposal of this paper is to share the knowledge learned in this new procedure and techniques implemented in HP/HT Unconventional wells, created by the Unconventional (UC) Drilling Department at Abu Dhabi which involve around ten different services, where each has a high importance and contribution for the collective success of the well at the moment to frac and hence the feasibility of the project. In order to assure the integrity and accessibility of the Frac String during Plug and Perf hydraulic fracturing operations of one of the toughest rock in Unconventional business worldwide, one procedure has been developed for running operations best practices. Pressure testing the Frac String (FS) during running in hole in stages while in vertical section to sure safe and successful Wireline setting and retrieving nipples plug with more than 30% solids in the system (high mud weight) to guarantee no leak in the string prior reaching total depth (TD). Hanging and testing cross over (XO), assuring compatibility with the wellhead connections. Cementing up to18.7 ppg. Flexible and expandable slurries, cement inside previous casing and apply pressure on surface to avoid gas percolation during the cement setting period. Cleaning out with Coiled tubing (CT) to ensure no obstruction and using different completion fluids for future accessibility. And finally, Pressure testing the Frac string up to 14ksi all are new practices and proven mitigation measures for all assessed risks for hydraulic fracturing operations. This paper is about sharing this new procedure in Abu Dhabi for having a cemented FS in UC wells High Pressure / High Temperature (HP/HT) with 100% integrity and internal accessibility to run plugs, perforations, logs and be able to apply high surface pressure to frac the tight reservoir in the planned zone, creating the desired permeability for future production.
There is no way to obtain zero injuries in any organization without the commitment of the workforce. This article will show how Abu Dhabi Company for Onshore Oil Operations (ADCO) Drilling Division and its contractors obtained employee commitment resulting in world class performance in HSE for the past five years and recorded the lowest Total Recordable Injury Rate (TRIR), the second lowest Lost Time Injury Frequency (LTIF) in ADCO's Drilling Division history and the longest time without LTI (Eighteen months without LTI) in 2011. In addition we have recorded zero car related injuries for the past four years and zero spills in 2011. DOIRC (Drilling Operations Incident Review Committee), a monthly meeting with all our contractors was a key factor in improving the safety performance of the drilling community by developing 360 0 communication between ADCO main office, ADCO field, Contractor's management office and their teams in the field .The forum also have shifted from a reactive committee where only incidents are discussed to a proactive forum where best practices are shared and a communication network was established to inform the fields on regular basis. In addition to that, High Profile Tours (rig visits by ADCO Top Management), DOIRC High Profile Tours (rig visits by ADCO and contractors Top Management), onsite workshops and regularly launching campaigns with our drilling contractor National Drilling Company (NDC) were the additional tools used to raise Drilling Division performance to a world class performance. ADCO Drilling Division has clearly established a successful formula for its safety performance to reach and maintain a world class performance for the past four years, reaching 0.52 TRIR in 2011 and 0.09 LTIF in 2008 and 2010;the lowest in ADCO Drilling history through effective communication culture. TX 75083-3836, U.S.A., fax +1-972-952-9435
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