Many cost components must be considered to determine the most cost effective deepwater production system for a particular site. Too often, only the well systems CAPEX 1 is adequately included in field development alternative studies. OPEX, RAMEX and RISKEX depend largely on reservoir characteristics, specific well system designs and operating procedures. The effect of these factors nearly always outweigh differences in well system CAPEX. Optimization of total lifecycle cost of deepwater production systems must include all of these factors.The risks associated with blowouts are often an important factor in choosing one dry tree tieback well system over another. Another important factor often overlooked is the cost of well system component failures. As oil exploration and production moves into deeper and deeper water, the costs to repair well system component failures escalate dramatically. This paper presents the methodology developed by a Joint Industry Project to quantify capital, operational, blowout risk and reliability costs associated with deepwater well systems. Five well systems have been modeled to demonstrate the methodology: a dual casing dry tree system, a single casing dry tree system, a tubing riser dry tree system, a conventional tree subsea system and a horizontal tree subsea system. Case examples demonstrate the model for these five well systems.The methodology, results and main conclusions from this Joint Industry Project are presented.
Field development profitability is a function of many income and expense factors such as capital expenditures (CAPEX), operating expenditures (OPEX), production rate, product price and the frequency of component failures. Component failures reduce the field total production rate and increase OPEX. The losses are directly drawn from the bottom line. Regardless of the chosen concept, the ability to efficiently keep production wells on stream is one of the most important factors determining field economic performance. When moving into deeper water, subsea interventions become more expensive and are associated with longer waiting times for the required intervention vessels. Furthermore, deepwater developments rely on new technology, which has yet to be field proven. This paper gives an overview of the challenges related to the selection of deepwater completion tieback concepts. There are number of different ways of developing oil production fields in deepwater. Dry Tree Tieback Concepts ("Dry") require a platform to support the permanently attached production/intervention risers, but provide the efficiency and the convenience of direct well access for remedial activities. Subsea Tieback Concepts ("Wet") provide greater flexibility in utilization of existing infrastructure, well location and development schedules, but require more challenging and costly well interventions/workovers. The fundamental question is whether the higher CAPEX of a dry tree tieback system is justified for the lower OPEX as compared with a subsea tieback system. The paper discusses the typical advantages and disadvantages with "wet" and "dry" tieback alternatives and outlines a method for how the experiences gained by the deepwater industry so far can be factored into business decision analyses that seek to evaluate the profitability of alternative field development concepts. Introduction The economics of deepwater developments are different from shelf activities. Deepwater is characterized by high capital expenditures with relatively low operational expenditures and high sustainable production rates - hence high costs for production interruption. Until recently it was quite common for the decision making process used to evaluate deepwater ventures to focus on optimizing the balance between potential revenue, (CAPEX) and operational expenditures (OPEX) according to the equation: Profit = Max (Revenue - CAPEX - OPEX) (1) The shortcoming in this equation is that it does not take into account unscheduled and unplanned events (such as component failures) that have the potential to shut down production for a long time, destroy a facility, pollute the environment and/or tarnish a company's reputation. When moving into deeper water, the economic penalty for delayed/lost production becomes greater. The uncertainty related to whether "unforeseen" events will occur is also increased as prototype and novel technology are introduced into an operating environment not encountered in shallow water developments. Furthermore, subsea well system repairs and interventions also become more expensive and are associated with longer delays due to availability and mobilization times for required repair vessels, particularly in ultra deep water environments.
The Paper presents an overview of the main design activities for the Completion and Intervention Landing String System that was deployed in the Tahiti field in the Gulf of Mexico. The functional and structural design challenges encountered due to the high operating pressures and temperatures are reviewed. The Paper also illustrates how analysis tools were used to quantify the observations found during test, and subsequently assist in determining a design solution. A key aspect of the design process was to view the design and operations from a holistic perspective by evaluating the design throughout its operational life. This paper will therefore present how this design process established a design solution that increased the reliability and confidence of the Landing String System and therefore reduced the operational risk. Introduction This paper addresses the technical challenges of developing a high pressure/high temperature (HP/HT) Completion and Intervention Landing Sting System for the Tahiti field in the Gulf of Mexico. As the project presented some specific operational challenges, traditional analytical methods were insufficient for the design process and a comprehensive test and qualification program was required to validate that the equipment proposed was fit for purpose. The paper presents an overview of the design methodology adopted and how the results from finite element modeling assisted in validating the test program. This paper also discusses the management of operational risk for HP/HT equipment and how the lessons learned during the design process will be addressed in future. The key areas of discussion are therefore as follows:The purpose and functionality of a Landing StringA review of the design methodology adopted for the Tahiti projectAn illustration of HP/HT analysis work performedThe management of operational riskA summary of operational performanceLessons learnedFuture work
fax 01-972-952-9435. AbstractAs our industry continues to move into the deeper waters of the Gulf of Mexico, we are finding more and more complex geologic structures, which present increasingly challenging drilling and completions requirements. Due to the geologic complexity, intervention will become an integral part of the reservoir development plan in order to achieve target recovery factors. After first oil, as the development moves into day-today production operations, subsea well interventions will play a significant role in maximizing production rates to keep the facility at maximum capacity. However, increased interventions will also carry additional OPEX impact. A significant challenge for any deepwater development is to identify the types, frequencies, and cost impact of intervention requirements over the life of the field. Since the ramifications of these issues are so diverse, it is crucial that the team which addresses this issue during the define stage of the project be representative of the stakeholders involved. They must take a holistic, or "Life of Field," approach to evaluating and modeling the anticipated intervention program, in order to achieve an optimum balance between CAPEX and OPEX considerations. Reservoir modeling, intervention modeling techniques, impact on well design, equipment selection, and drilling and intervention vessel strategy will be addressed, as each are related to and affected by the Life of Field approach.
fax 01-972-952-9435. AbstractThe Paper presents an overview of the main design activities for the Completion and Intervention Landing String System that was deployed in the Tahiti field in the Gulf of Mexico. The functional and structural design challenges encountered due to the high operating pressures and temperatures are reviewed. The Paper also illustrates how analysis tools were used to quantify the observations found during test, and subsequently assist in determining a design solution. A key aspect of the design process was to view the design and operations from a holistic perspective by evaluating the design throughout its operational life. This paper will therefore present how this design process established a design solution that increased the reliability and confidence of the Landing String System and therefore reduced the operational risk.
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