A polycrystalline diamond compact (PDC) bit was used to drill a northern Kuwait well. The typical casing design for this field calls for the 16-in. section to be the longest section in the well, which extended from 1,230 ft to 6,000 ft for a total of 4,770 ft in this particular well. The formations drilled in this section were mainly comprised of carbonates interbedded with shale. The first 2,000 ft of the section was highly interbedded with hard and soft layers of carbonates with the unconfined compressive strength ranging from 6,000 psi to 30,000 psi. Additionally, the remainder of the section had hard stringers with unconfined compressive strength up to 30,000 psi. Such highly varying and highly interbedded formations tend to damage the PDC cutters because they are more susceptible to impact damage. For this reason, roller cone bits with tungsten carbide inserts (TCI) are preferred and are typically run in this section. However, the rate of penetration (ROP) significantly decreases when the TCI bits drill through the hard formations. For this reason, the operator and service provider established an objective to design a PDC cutting structure that would efficiently drill through the hard interbedded formations and complete the section in one run, achieving higher ROP than was achieved with the TCI bits in the offset wells. Based on the formation strength information available, the decision was made to initially use a 6-bladed 16-mm cutter. The service provider then recommended using conical diamond elements (CDEs) and placing them behind the primary PDC cutting structure. The conical shape of the CDEs penetrate the high-compressive-strength rock, effectively weakening the formation with a plowing mechanism. Furthermore, the CDEs also protect the PDC cutting element from impact damage. A high-performance motor was also recommended to reduce stick-slip. A finite element analysis (FEA)-based modeling system was used to comprehend the dynamic behavior of the bit and bottomhole assembly (BHA) design. The most efficient bit design was selected, and changes in the BHA were recommended to deliver the most stable and optimized drilling system. A detailed drilling parameters sensitivity analysis was performed, and a driller's parameter plan was prepared to provide enhanced drilling parameters for mitigating downhole vibrations. As a result, the CDE bit drilled the entire section, achieving an increase in on-bottom ROP by 24%. In the hard formation—where the ROP of TCI bits would typically decrease—the CDE bit drilled at twice the normal ROP. The CDE bit technology proved to be efficient in what was previously thought to be a roller cone application. By reducing the drilling hours needed to complete the entire 16-in. section, the CDE bit saved the operator 3.5 days of equivalent drilling time.
The Late Neogene Baram Delta province developed on an active margin located offshore Borneo in Malaysia. The field has been in production since 1982, and a total of 64 wells have been drilled from three (3) platforms. This paper discusses the process used to locate remaining oil for infill drilling. This involved a multidisciplinary effort including geology and geophysics, reservoir engineering, drilling / completion, and production technology. The geologic and geophysical (G&G) assessment consisted of updating the static model and constructing mobile oil thickness and structural and bubble maps of all reservoirs. These maps were used in conjunction with original and current fluid contacts and helped to identify and locate remaining oil accumulations. The target portfolio was screened and ranked, and preliminary wellbore paths were built. Four (4) new wells and eight (8) sidetracks combining either shallow or deep targets were passed on to the reservoir engineering team for optimisation from simulation models and first-pass estimation of oil incremental reserves. Reservoir simulation focuses on optimising target intervals as determined through G&G work and drilling design. Well constraints are set to be consistent with operating field production practices and facilities constraints. Completion intervals for the dual-string wells are optimized to minimise water cut and maximise oil rates. All simulation results are rigorously checked against offset well production and observed properties. Once drilling targets are risk-assessed on the basis of structural, fluid contacts, and properties uncertainties, the final well trajectories are designed by the drilling team. This study identified and ranked multiple undrained and appraisal areas. A full infill redevelopment consisting of more than 10 accelerated wells planned through the utilisation of existing facilities was presented and approved by PETRONAS Carigali Sdn. Bhd. (PCSB). The well and target portfolio is focused on three (3) main field development areas: Attic oil in shallow Pliocene reservoirsNew development areas in deeper Miocene levels on the southern blockUntapped deep Miocene reservoirs on the northeastern flank in crestal location The first two (2) sidetracks and three (3) workovers were successfully completed in December 2012, and the current oil production is 40% higher than originally estimated. The successes to date have proved the effectiveness of the concepts that were applied to identify and develop the remaining oil, and the field became East Malaysia's top producer.
In 2012, a redevelopment infill drilling campaign took place in a brown field, offshore Malaysia. Accurate wellbore positioning was critical to place a well within a path that navigates 2200 ft through an antithetic faults panel, separated approximately 900 ft, and with a 120 ft general throw; and to intersect the five target reservoirs of the well. The complex well path also faced the challenges of infill drilling in a brown field, such as collision avoidance in a crowded field, the location of the target reservoirs relative to the available drilling slots; as well as trajectory restrictions due to completions design. This paper presents the well design solutions that include a rigorous anti-collision analysis and a comprehensive survey programme. The survey programme consists of gyro while drilling (GWD) on the upper section of the well until the path is clear of magnetic interference from neighboring wells and the application of in-field referencing (IFR) correction for conventional measurement while drilling (MWD) magnetic survey based on accelerometers and magnetometers. IFR improves survey accuracy with a multi-station analysis that corrects the survey error with the localised crustal effects in the magnetic field of the earth. It was used for well positioning in between faults and for target intersection. It enabled drilling the well with higher confidence while intersecting the target reservoirs. A reduction of 60% on survey uncertainty was observed. The more accurate wellbore survey also optimises collision analysis for future well plans and it gives more reliable control points to update the subsurface static model. The benefits were obtained without compromising the drilling performance given that no extra operational time is required for the survey correction. Introduction Context The well is located in a brown field, offshore Malaysia. Three infill drilling campaigns have been executed since a decade ago to increase oil recovery. To maximise the use of existing assets and to optimise cost, infill drilling has been performed from existing drilling facilities by either accommodating new drilling slots or side-tracking idle wells. The well was planned to target several reservoirs located in crestal position in the southern block of a rollover anticline formed by growth faulting. In the study area, faults show a general east-west trending direction. The reservoirs are entirely related to sealing against faults while within reservoirs the seals are marine flooding surfaces. Well design considerations The well design process consisted of identifying the available surface location -a well with high water cut, idle since 2007- and selecting the subsurface targets. Once drilling targets were identified and preliminary well trajectories were built, an integrated team approach was used to optimise the well paths, usually requiring a compromise between the desired and the practical approach.
This paper describes the application of casing drilling technique for the top hole section in conductor sharing wells in a brown field, offshore Malaysia. Its objective is to describe the integration of the casing drilling technique and the conductor sharing design when used in conjunction. It is intended to share the challenges faced during the design and execution phases of the project, the solutions analyzed and applied; as well as the outcome and learnings. In this case study, the conductor sharing design makes it possible to maximize the well capacity of the offshore drilling platforms by accommodating multiple wells per drilling slot. The casing drilling technique is implemented to manage drilling risks related to wellbore stability, losses and shallow gas. The feasibility for combining the two technologies is evaluated during the planning stage by reviewing the documented previous industry experience of the two technologies, combined or separate; while local knowledge is analyzed to ensure all drilling factors are considered. Solutions to challenges such as wells interface inside the shared conductor, directional control, losses, cement design and placement techniques, well control, operational procedures and time and cost efficiency are analyzed. The execution results are analyzed by comparing design estimations and assumptions with field data and actual results. These data is translated then into recommendations and lessons learnt. The conclusions of this case study are presented as a set of design work, drilling practices and risk analyses processes and their results that can be replicated or considered in future wells design where conductor sharing and casing drilling are to be implemented together. While several individual studies of particular conductor sharing wells configurations, casing drilling and well construction techniques are available, the present work discusses one of the few applications to date where conductor sharing and directional casing drilling technologies are combined to address specific offshore challenges. The team considers of paramount importance that the knowledge obtained on this very specific combination of two technologies is documented and shared within industry professionals to provide reference for future applications.
A Workover or sidetrack is often performed, in brownfields, to revitalize idle wells or to produce alternate zones. Recently, with a larger number of fields being redeveloped; the proper plug and abandonment (P&A) of donor wells gained relevance. This is a study of the evolution of the P&A methodology in a brownfield, offshore Malaysia, where engineering techniques and risk management strategies have been developed into a consistent approach to well P&A. The methodology has allowed economic access to reserves and has become a process that can be applied across the field based on well configuration, best practices and current technologies. The operations entail not only intervening wells for gravel pack removal, fishing of mechanical obstructions and retrieval of completions, but also isolation of completed reservoirs from surface whilst isolating cross flow between them, which is of paramount importance in a brownfield with plans for future enhanced oil recovery (EOR).Challenges, such as lack of information and the uncertain condition of ageing wells related to corrosion, leaking elements, zonal isolation, annulus pressure and well integrity; as well as inadequate maintenance, mechanical obstructions and failure of existing downhole equipment have been successfully managed in all cases.Key processes include extensive data gathering and upfront well investigation and preparation for contingency planning. The wells sequence has been optimized to minimize the impact of un-foreseen events; and the decision making process has been drafted to cover for a wide range of situations.Results show reserves that have been accessed at 40% the cost of a sidetrack, by retrieving old gravel pack assembly and workover the well; also, sidetrack wells have enabled reaching reserve opportunities in the field without the costly addition of slots to offshore platforms. This consolidates the methodology for its further application in the field with the potential to be implemented on other similar redevelopments.
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.