Water coning in oil reservoirs pose serious hindrance to optimizing oil production as unwanted fluids tend to replace the oil in the production stream, which invariably limits the ultimate oil recovery. The coning of water into production wells is caused by pressure gradients established around the wellbore by the production of fluids from the well. These pressure gradients can raise the water-oil contact near the well where the gradients are dominant. Many methods have been published for evaluating and combating coning tendencies in the wellbore, yet water coning are still a major issue in many oil fields all over the world. This article examines the various approaches of controlling coning of unwanted fluid in the wellbore thereby optimizing oil production from the reservoir.
Most reservoir in mature oil fields are vulnerable to challenges of water and/or gas coning as the size of their oil column reduces due to extensive period of oil production. These often result to low oil production and excessive water and/or gas production. This study therefore seeks to evaluate the occurrence of coning through the movement of fluid contacts in mature oil field reservoir. MBAL petroleum software was used to study the tendency of coning in mature oil field in the Niger delta. Using reservoir production history; fluid saturation, initial pressure, initial fluid contacts and depth data, a simulation was run to predict the future movement of oil-water contact and gas-oil contact with declining pressure. Using the interception on a plot of oil-water contact and gas-oil contact against time, a point where both water and gas are likely to cone was identified. Sensitivity study was also carried out to evaluate the trend of the critical rate with the reduction in oil-column due to the shrinking fluid contact. It was observed that the critical rate reduces with declining oil rim fluid contacts. Therefore to avoid coning in mature oilfield rim, the critical rate of the respective decline in oil column thickness is determined to maximize oil production.
Intelligent Reservoir Management and Monitoring has played a key role in the pursuit of improving the hydrocarbon recovery and reducing the development expenditure in the challenging multi-stacked compartmentalized fields which have proved to be perplexing in a number of ways which include preventing or delaying water breakthrough, extenuating wellbore instability, sand production etc.
Reservoir-management and monitoring options have been greatly improved in recent decade by smart completions comprising of downhole monitoring and control equipments like permanent down-hole gauges to have "eyes" into the reservoir and to monitor performance for each zone; dynamic active flow control valves, which aid in equalization of the reservoir inflow into the wellbore; and the SCADA system which enables the real time monitoring and control of the downhole and surface equipment remotely from the control room.
Proper application of this methodology can be one of the most lucrative ventures that an operator undertakes, by delaying water breakthrough problem to recover additional monthly cumulative production than a conventional production method in such reservoirs. This method also results in avoiding the heavy intervention expenses, extending economic life of the field, improving reservoir management, zonal isolation, allowing real time well testing, fewer wells and less operating expenditures.
This paper discusses real field design methodology and outcomes of different wells that resulted in restoring the production by greater than 1000 B/D, minimizing the OPEX by eliminating huge cost oriented interventions of $10 MM (per intervention), saving Millions of Dollar investments as CAPEX via IWC re-completion with multi-lateral technology and an augment of EUR of about 2 MMSTB per well. The paper also enlightens a comprehensive logic guideline towards the tool box of the technology, including the applied workflow, procedures and standards with the field examples and desired results.
In the quest of improving the hydrocarbon recovery and reducing the development cost in the challenging multi-stacked compartmentalized fields as well as oil rim reservoirs in Malaysia, well type and completion design was found to play a major role. Intelligent well design and completions, namely multi-lateral, selective and controlled injection and depletion, dynamic active flow control valves and down-hole pressure/temperature/composition monitoring have been identified as an essential component in the enhancement of the development strategy. Smart/intelligent completions have the ability to prevent/delay water or gas breakthrough, increase the productivity index and also to properly control drawdown to mitigate wellbore instability, sand failure and conformance issue. Active flow control valves also allow for fewer wells to be drilled by enabling efficient commingled injection and production wells. Moreover, with down-hole monitoring and surveillances, unplanned and challenging work-overs can be avoided, further reducing operating costs. The study also focuses on well architecture that entails well type selection, well reservoir penetration, well inclination and orientation, well completion simplification, well placement and well-count optimization.
In this paper, examples of mature complex multi-stacked and compartmentalized reservoirs with very thin to thick oil columns have been studied for improving the development and exploitation strategies through application of intelligent well type and optimum completion design and engineering. The suggested technology tool box including the applied workflow, guideline, procedures and standards with the field examples and desired results are to be presented and discussed. The study will cover from the assessment to the implementation and execution as well as the modeling methodology of the smart well technology on the selected fields in Malaysia.
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