Casing-while-drilling is a relatively new well construction process or technology for simultaneously drilling and casing a wellbore, and has been utilized globally over the last 15 years or so. This technology has shown advantages of reducing overall drilling time and cost. It has demonstrated signs of reducing hole problems, such as mud losses, through plastering effect because of the rotation of the casing string against the formation. It provides assurance to case off unstable formations while drilling, resulting in significantly reduced well construction costs. Saudi Aramco has made several field test runs of this technology beginning in early October 2008, including deployments of both simple casing drilling with drill-through casing bit (non-retrievable) system and advanced bottom hole assembly (BHA) retrievable system designed for directional casing drilling. This paper will document the lessons learned from implementation of the technology, including planning and design, rig operations, problems encountered, modifications made to reduce risk after extensive review and investigation, and finally, successful deployment of a directional casing drilling to the planned casing point with a 17" x 13-⅜" system. In addition, the paper briefly outlines the further required improvements of casing drilling tools to ensure continued success in the future.
Summary Reactive formations, resulting in wellbore instability, can obstruct the running of casing, liners, and completions. This problem is particularly acute in highly deviated, complex wellbore geometries, and long horizontal sections, where increased exposure time can lead to deteriorating hole conditions. This paper reviews the use of a novel fluid-powered Turbine Reamer Shoe (TRS) to successfully run 9⅝" casing, 7" drilling and production liners, and 4½" liners and completions through problematic intervals and hole conditions. The downhole turbine provides high speed reamer rotation without rotating the entire string, and requires minimal modification to standard running practices. The 9⅝" and 7" casing/liner running turbines present a further novel design feature: an unobstructed through bore (at API drift ID of the string on which it is run) for rapid drill out and drilling ahead. Results from over 30 onshore and offshore wells from the Manifa development, and several other fields, including Berri, Zuluf, Qatif, and Safaniya are analysed. The TRS is now becoming a technology of choice in the planning of challenging wells, to mitigate the risk of sticking, and to reduce the flat time and HSE exposure involved in conditioning the wellbore and re-running casing, liners, and completions.
Saudi Aramco operates one of the largest offshore oilfield developments in the world. This field is made up of 41 kilometers of causeway, 3 kilometers of bridges, 27 drilling islands, 13 offshore platforms, and 16 onshore drill sites. The magnitude of the field has pushed cutting edge technology and processes to the forefront of the industry. This new development has driven achievements in multilateral and extended reach directional wells. One challenge the operator faces is to maintain proper hole cleaning in extended 8½ in. tangent sections at a 85-87°inclinations, which are drilled in excess of 10,000 ft.Historically, drilling very long tangent sections required the use of several tandem sweep pills, wiper trips, and reaming/back reaming to maintain hole quality and efficiently remove cuttings bed from the wellbore. The negative effects of poor hole cleaning can lead to tight intervals, increased torque and drag, and eventually stuck pipe.In an effort to drill efficiently, utilization of a new technology to increase the cutting removal was trial tested on well A1 from an onshore location of the field. The ERD well, A1, was drilled to a total depth of 30,480 ft MD (8,650 ft TVD) into a stratigraphic environment composed of limestone, shale, and siltstone. The objective of the trial test for the tool was to improve the drilling efficiency. To obtain the best possible hole cleaning, a simulation was performed by placing the tools every three stands along the tangent section in the 8½ in. hole section.The goal of the trial test was to achieve the following:• Enhance hole cleaning by removal of cuttings bed.• Reduce the frequency/number of tandem sweep pills.• Reduce the frequency/number of wiper trips.• Reduce torque and drag and compare it with the offset wells.• Reduce drilling cost.A service company installed a cuttings flow-meter system at the shakers, which was used to evaluate the hole cleaning efficiency and performance of the hole cleaning tools. This paper will demonstrate the systematic methodology, which Saudi Aramco and the service company used to approach the utilization of the hole cleaning tools to achieve a clean hole in well A1.
Offshore fields in Saudi Arabia are being developed based on optimum use of onshore drilling rigs. Rather than developing the field completely from offshore platforms, it is developed partially from man-made, interconnected drilling islands. Extended reach wells (ERWs) are necessary for optimum surface location use and maximum reservoir contact. As the wells increase the step-out, challenges arise not only during the drilling phase but also while running liners to target depth (TD). Wellbore geometry, hole instability issues and torque and drag forces, restrict the ability to deploy the liner to planned depths, setting technical limits to the oil and gas production potential. The main challenge of running liners through extended lateral sections is the lack of hookload to push the liner to TD, and the ability to rotate the drill pipe without rotating the liner. As more extended reach deployment becomes common practice, it is necessary to implement new running liner practices and tools that rotate the drill pipe above the liner, to break the frictional drag and make more surface weight available, to deploy the liners or completions to TD. This paper outlines the problem faced when deploying 7 in. liners in ERWs through 8½ in. hole lateral sections, and the solution using an innovative rotatable friction reduction tool, which allows the rotation of the drill pipe without transmitting torque to the liner. A case study is presented showing the main challenges, pre-job engineering calculations, field implementation, final results and lessons learned. Ultimately, the new rotatable friction reduction tool was a key component in the deployment of the longest 7 in. liner run in Saudi Arabia so far.
Reactive formations, resulting in wellbore instability, can obstruct the running of casing, liners, and completions. This problem is particularly acute in highly deviated, complex wellbore geometries, and long horizontal sections, where increased exposure time can lead to deteriorating hole conditions. This paper reviews the use of a novel fluid-powered Turbine Reamer Shoe (TRS) to successfully run 9⅝in casing, 7in drilling and production liners, and 4½in liners and completions through problematic intervals and hole conditions. The downhole turbine provides high speed reamer rotation without rotating the entire string, and requires minimal modification to standard running practices. The 9⅝in and 7in casing/liner running turbines present a further novel design feature: an unobstructed through bore (at API drift ID of the string on which it is run) for rapid drill out and drilling ahead. Results from over 30 onshore and offshore wells from the Manifa development, and several other fields, including Berri, Zuluf, Qatif, and Safaniya are analysed. The TRS is now becoming a technology of choice in the planning of challenging wells, to mitigate the risk of sticking, and to reduce the flat time and HSE exposure involved in conditioning the wellbore and re-running casing, liners, and completions.
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