A cost-effective water management strategy for the thermal development should ensure the availability of right quality and quantity of water during the lifetime of the field. This paper presents an actual case for field water management, which includes availability, use, re-use and safe disposal of both source and effluent water. Thermal projects are notorious for their large volume of produced water through the life of the field. While treatment of produced water is a major issue; in a country like Kuwait where water is scarce, part of the produced water need to be recycled and re-used for steam generation. The methods and procedure followed are based on the practices used in the current Large Scale Thermal Pilots (LSTPs). The process involves field observations and performance, facility set-up and limitations, technical analysis and mitigation plan; so as to reach to an efficient water management plan and deliver better quality water. Heavy oil field development in Northern Kuwait is currently one of the few thermal "mega-projects" in the world. The development started initially with Cyclic Steam Stimulation (CSS), followed by Steam Flood (SF). These projects need dedicated used water disposal wells. Water disposal wells, initially completed, showed poor injectivity even after CTU acid stimulation with 15% HCl. Based on lab test results and analysis, injectivity was restored with suitable anti-scalant injection and precipitate removal. Another aspect of these wells was the injection casing shoe-setting depth. A multi-disciplinary team reviewed and established the optimum placement interval for shoe that meets the regulatory and design criteria. The new shoe setting-depth eliminated repeated well interventions during the life of these wells. The learnings were disseminated to various other projects within the company. Quality of source water was also a focus area for the team. Water quality of the source water at various depths were analyzed and tested. Based on the results, optimum well depth and location was ascertained which resulted in improved water quality and quantity. A novel approach, with key focus on competitive scoping and sustainable development and the combined effort from various stakeholders through an integrated approach have enabled significant savings to reduce the cost of this project. The learnings gathered, and the uniqueness of the project will add significant value to similar projects elsewhere in the world.
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.
Workover operations in shallow low pressure heavy oil unconsolidated sandstone reservoir in Kuwait presents a major challenge due to significant killing fluid loss which causes wellbore plugging, incremental operational costs due to more rig days, excess brine volumes, and more importantly the impact of deferred production due to formation damage. This paper presents an innovative fluid-loss control pill added to killing fluids, which has resulted in significant cost savings and well productivity improvements. The subject heavy oil reservoir have formation pressure equivalent to 6.3 PPG versus 9.3 PPG Potassium Chloride brine used as killing fluid. This overbalance condition is a requirement as safety barrier but conversely it leads to hundreds of barrels of killing fluid losses with the consequently invasion and formation damage. Kuwait Oil Company recently added a new customized fluid loss control pill of high purity vacuumed dried evaporated salt to the well killing procedure. Using this fluid loss control pill both drilling and reservoir engineers achieved their aim in terms of safety operation and no formation damage. To test this new pill, two shallow wells with 220 psi reservoir pressure and perforation set at 630 ft were selected to record the losses. The first well had undergone workover including recordings from caliper, cement, and ultrasonic logs, which measured the positive impact of the new control pill on logs quality by excluding fluid pumping while logging and having constant fluid level at surface, which saved cable head from unnecessary tensions. In a second well, there was hanged standalone screen on a packer against the perforation and there is no direct access to the perforation. The control pill was customized to be pumped into the screen, which sealed the screen itself perfectly. The control pill flowed back easily in both wells and same loss rate was observed after removing the pill, which confirmed no negative impact on reservoir permeability. KOC confirmed that the two jobs were successful and the pill to be approved for full field implement in other operations. The achieved success criteria summarized as follows: Hydrostatic column is a safety barrier that assuring fluid level at surface during workover is safety requirement especially in high Gas oil ratio wells.Full circulation enhances sand cleanup operation.Fluid level at surface results in accurate logging by eliminating invasion into reservoir and support improved operations.
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