Long-extended reach drilling (ERD) well has become necessary to reach untapped resources. This paper will describe pre-planning, execution and post results of drilling ERD wells with large bore design of 12¼" as the main step out section and deploying 9⅝" casing on shallow TVD of 4,200’. Progressive increase of the ERD ratio and complexity from one well to the next was planned and executed till we reached the longest well deploying 8 KM of 9⅝" casing with 5.4 ERD ratio at 26,179' TD horizontally all the way. A learning curve was established on drilled wells while progressively increasing reach and complexity. Subject well was the longest of any well planned in the field by far. Success involved implementation of technically modeled engineered solutions and verified during execution. Operational procedures including but not limited to: proper planning and execution of well profile to ensure optimum placement in a specific formation and minimum side forces. Drilling and tripping procedures to ensure the lowest friction factor (FF) and allow drilling to target depth (TD) with optimum rig capability. Engineered solution for casing running technologies, which involved rotation and conventional running and floatation. The longest ERD well was drilled to 26,179' TD with field ROP record in 12¼" hole section, maintaining very good hole quality proved by smooth bit trips out of hole and the final trip at TD on elevators. Hole cleaning and fluids strategy was developed and executed efficiently to measure FFs as low as possible for successful 9⅝" deployment. Engineered solution was proposed for 9⅝" deployment and was successfully trial tested on a shorter well to validate simulations. Casing rotation FFs came close to the modeled FFs. The 9⅝" Casing was deployed to bottom as planned and the cement job was performed successfully. Various records were achieved: the subject well achieved the deepest 9⅝" horizontal casing, the deepest 12¼" horizontal at TVD shallower than 5,000'. The longest 12¼" horizontal open hole at TVD shallower than 5,000' with section footage of 16,164'. The 9⅝" casing was deployed as a long string, eliminating the cost and challenges of a liner hanger and the need for a future tieback and also keeping hole sizes available for main and contingency sections to drill the reservoirs ahead. In addition to existing developed procedures and practices for ERD wells, subject well was dealing with the challenge of drilling a long 12 ¼" hole with a torque limitation of 30K lbsf.ft on TDS, and 4200 psi on surface equipment, and running the longest casing horizontally at such a shallow TVD, which is being done the first time globally. The success proved that challenging ERD wells can be drilled with optimum investments on rig capabilities.
The efficient placement of cement as a verified barrier above a distinct permeable zone in any oil and gas well is a constant challenge faced by the industry. Absence of isolation behind the casing represents a deficiency to the required well integrity barriers. A compromised well barrier may result in casing corrosion, leaks, and eventually sustained casing pressure which might lead the loss of the asset and/or endanger the safety or workers and/or the environment. Ultimately, a compromised barrier implies compromised well integrity. Fluid displacement in ERD wells is different from conventional wells and the job conditions pose additional challenges. To ensure adequate cement placement in this ultra-ERD well, several challenges had to be addressed. Hence, an optimized cement placement method that focused on ECD management to prevent induced loss circulation included maintaining fluids displacement regimes, fluid density, and hydraulic friction hierarchy. Moreover, casing centralization was imperative. Limiting casing string movement once the string deployed successfully to bottom equally added to the challenge. A system's approach was utilized to achieve the level of optimization desired. Slurry rheology and fluid loss control were adjusted. A pumping schedulethat ensured that optimum displacement efficiencies were achieved in line with the designed rheology was used. The impact of pump rates on downhole ECD regimes were equally evaluated and confirmed to be fit-for-purpose. Mud conditioning prior to the cement displacement and spacer wettability were also of paramount importance. A centralizer spacing resulting in >70% stand-off was utilized. These optimized practices represented the results of 3D modeling used to understand the fluid dynamics, and its distribution under the influence of a horizontal static pipe. This work also presented a comprehensive sensitivity analysis not only on the effects of thermal thinning on fluid rheology, but also on gravitational forces acting on the fluids in an ERD well. After execution, a combination of cement bond logs, ultrasonic measurements, and advanced interpretation techniques were used to evaluate the cement bond quality. The logs showed an improved cement bonding with minimal to no channeling, and excellent radial cement coverage. As global hydrocarbon resources become harder to reach, ERD wells maybe required to access such subsurface targets. Adequate cementing well integrity is crucial to assuring the long-term integrity of such wells for the economic life of the assets. The practices implemented in this case history will contribute to expanding the tools and techniques available to engineers to achieving excellent barrier isolation in such wells.
Applying new technologies to improve existing methods or techniques can be important to successfully delivering high-profile ultra-extended-reach-drilling (ERD) projects. The underreaming-while-drilling technique in ERD projects represents such an opportunity. Recently, a 14½-in. borehole required being enlarged to 16 in. due to complexities, including surface location constraints, longer stepout, and borehole instability. This paper presents the challenges, how they were addressed, and the results. A dynamic modeling system was used to model the planned drilling operation based on offset well data. The extensive engineering studies included a finite element analysis (FEA), which modeled the cutting interface designs for drilling rocks. This analysis emphasized the importance of the compatibility between the underreamer cutting structure and the drill bit, which can help to predict the drilling performance while eliminating costly trial-and-error field tests. The analysis also enhances drillstring dynamic behavior to diminish erratic torque while maintaining directional control. Taking on a challenging target dictated a multidisciplinary approach to achieve what was previously considered an impossibility. The 14½-in. borehole was enlarged to 16-in. while landing at a 90° inclination successfully for the first time worldwide in an ultraERD profile. Several notable challenges were observed during the drilling phase, which required reevaluating the initially planned operations. A significant level of shocks and vibrations were observed, which required the bottomhole assembly (BHA) design to be further optimized in terms of bit cutting structure and string stabilization. The rate of penetration was optimized using real-time data from downhole drilling mechanics. The FEA results also allowed for developing an optimized drilling parameter plan for steering across the different formation horizons to be intercepted during the drilling operations. The mechanical specific energy was used as a monitoring tool to gauge drilling performance efficiency. Together with the mechanical specific energy, the plan for drilling parameters was adjusted in real time to deliver optimal BHA performance and ensure that no BHA vibrations, axial, torsional, and lateral, negatively impacted on the rock cutting process. Connection practices were also modified to account for pilot BHA length. The successful implementation of underreaming while drilling resulted in a significant savings in rig time, and subsequent cost savings equivalent to 20% to 30% of the section authorization for expenditure. The potential benefits resulting from using existing enabling technology to further realize significant project savings exists. The application of underreaming while drilling is unique in the sense that the ERD requirements of the project are on the extreme scale of footage drilled and borehole size drilled horizontally. Lessons learned can be applied to similar projects to help shorten associated learning curves, improve project efficiencies, and ultimately ensure optimum delivery of high-quality, large, ERD wellbores.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.