This paper discusses the approach of Cairn Energy India Ltd. (CEIL) in the use of a state of the art technology that integrates all relevant data scenarios for designing and planning development wells in the Mangala field of Western Rajasthan, India.To improve the quality of the well planning process, CEIL has realized the importance of a collaborative well planning environment, which was implemented by means of its world-class 3D visualization center that enables multidisciplinary well planning workflows to take place in the subsurface environment. The environment includes physical infrastructure, new technology, and data. A fully functioning collaborative well planning environment enables the drilling team to plan wells using engineering tools, including drilling target definition and refinement, well pad positioning, and wellbore position uncertainty, based on company anti-collision policies, with geosciences team capacity to validate those designs against their subsurface data.The Mangala field development process has established the success of CEIL with rapid, multisolution iterations well planning to the entire asset team and improved wellbore positioning based on potential engineering constraints. This process takes the optimum reservoir drainage into account with possible geological hazards and reduces the operational cost by complementing technical expertise across the broad disciplines. The workflow aids wellbore and drilling optimization and improves decision making and collaboration throughout the field development sequence.The paper explains the detailed aspects of collaborative well planning and optimization of well placement methodology used for Mangala field, which includes 11 horizontal wells that were largely designed as shallow extended reach drilling (ERD) wells. It demonstrates how this method significantly improved the mutual workflow between departments and increased efficiency. This paper also describes the interactive design that dramatically decreased the cycle time in planning more than 160 wells in the field, which contributed to effective development plans and well placement based on geological, drilling, and completion requirements. IntroductionThe level of complexity and difficulty of performing planning phases has increased over the last two decades, especially in those cases that require collaboration among all disciplines, including drilling, geology, geophysics, and reservoir characterization. This process collectively demands the respective professionals to contribute their expertise in optimizing the well. The ability of each discipline to rapidly create and evaluate a mixture of alternative development plans and to efficiently make key decisions during the planning stage provides the most value to the overall development project.CEIL has deliberately worked toward improving its existing resources, including the people, facilities, hardware, and software services, because only with this new method of working will it revolutionize the way that people manage their day-to-day ass...

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A carbonate reservoir in the Tarim oilfield has a deep burial depth (5000 to 7000 m), high temperature (130 to 150°C), and long horizontal section (600 to 1600 m). It is a heterogeneous formation with obvious interlayer physical differences. The requirements for using a multistage acid fracturing process (5 to 12 stages) in the stimulation program for this complex horizontal well completion highlight the challenges associated with ensuring tubing string integrity. Multistage acid fracturing string design is more difficult than conventional string design because the tubing string consists of multiple packers and sliding sleeves, which can allow for uneven fluid inflow distribution through the variable cross section. Thus, to understand the pressure decline profile resulting from localized heat loss, an accurate pressure and temperature simulation is important. The horizontal well process of running in—setting—release—tie-back complicates the calculation of initial conditions for string mechanics analysis. The tubing string operation process can be very intricate; as such, a proper tubing string stress analysis should consider the operation characteristics adequately. Based on technological characteristics, this paper introduces, in detail, a string design flow for the staged acid fracturing of a horizontal well. This paper provides detailed descriptions of the anticipated loads encountered during multistage acid fracturing, using a wellbore thermal and flow simulator to perform wellbore temperature and pressure simulation under different operation scenario conditions. In a standard tubular design study, a comprehensive model that includes the well configuration with the tubing string structure and operation characteristics is essential to adequately simulate the potential stress placed on tubing, packers, and sliding sleeves. This also would help to optimize the design of the tubing string composition and operational parameters. In view of the technological characteristics of acid fracturing strings for horizontal wells, this paper focuses on the introduction of design methods and considerations. An example horizontal well is used to describe the analytical process of string mechanics for staged acid fracturing.

In 2011, a major exploration and production oil company drilled and tested an HPHT well, the Tong Rang 3. This well is located in Bongkot field, Gulf of Thailand, about 722 km from Bangkok. This paper highlights the outcome of a post-drilling review using the Tong Rang 3 as a case study with respect to the well-design models and steps that the company will be taking towards optimizing its higher degree of HPHT development wells, which include future challenging prospects in the Gulf of Thailand.Aside from stress and pressure profiles, a good understanding of the temperature regime and heat transfer in HPHT wellbores is an important aspect of the planning process. The logs and actual well-testing operations in the Tong Rang 3 confirmed that the hydrocarbon produced contains gas condensate with 31.5% CO 2 . The maximum circulating temperature was diagnosed to be around 207°C while drilling to TD with a mud-cooling system in place and bottomhole temperature in excess of 227°C during well testing and a tubing-head temperature of 60°C.To improve the quality of the well design and planning process, the company has realized the importance of a case study to establish a guideline in their well-integrity process, thereby allowing the drilling team to plan similar wells using proper engineering assumptions, including basis of design refinement, based on the company's well engineering policies. The study will not only enable aiding the wellbore and completion optimization, but can be used to improve decision making throughout the field-development campaign, thus avoiding possible underdesign and achieving long-term well integrity and cost optimization. This paper will detail aspects of the well design incorporated in the Tong Rang 3 and provide a discussion and comparison between the plans vs. the actual design throughout the execution of this HPHT well, focusing on advanced tubular design from a temperature simulations aspect. It will also highlight the effect of tubular heat-up through comprehensive sensitivity analyses, while understanding how the currently available technology can be used to support an integrated basis of design model to successfully establish a representative HPHT wellbore configuration, subsequently signifying relevant well-construction parameters to ensure an effective and safe design for future HPHT wells.

A casing wear assessment was implemented as part of the workflow and methodologies for an operator well design process to better anticipate the critical failure mode of a tubular string. Because the reduction in tubular string wall thickness as a result of drilling and workover operations has been an ongoing concern within oil and gas field development, casing wear modeling with a workflow to accurately predict wear and minimize uncertainties is vital to maintaining well integrity throughout its lifespan with minimal or zero intervention. Because of multiple high-angle lateral branches drilled in lateral wells, the wear factor should be understood while managing casing wear. Wellbore and drillstring geometry can incur high lateral loads on tool strings and production casing, causing possible excessive casing wear. This wear reduces both burst and collapse ratings of the casing and can wear through the casing, resulting in costly remedial intervention measures for mitigation. This paper provides an integral insight for production casing wear focusing on a lateral well simulations study of the underlying wear factors ranging from the base case to the worst case. This enables a proper assessment in the well design by means of casing integrity, particularly for multilaterals and deep and/or long horizontal wells. A simulation and detailed workflow on how to incorporate its results into a multilateral/highly deviated casing design and stress analysis are discussed, thus providing an integration process resulting in improved anticipation of the critical failure mode for the investigated tubular string for this type of well.