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Wells 1A, 2A, 3A & 4A are designed as four (4) horizontal oil producers to maximize the oil recovery from the XXYY heterogenous sandstone reservoir in Offshore Malaysia. The reservoir has been producing since 1975 on natural depletion before gas injection (1994) and water injection (2019-2022) were introduced. XXYY reservoir is expected to have wide permeabilities ranges from as low as 1-mD to 4-D and high uncertainty of gas-oil contacts from recent saturation logging acquisition. Coupled with the complex reservoir nature of massive gas cap and thinning oil rim observed between 30-50ft-TVD, historical production of oil with optimum GOR in XXYY reservoir remained the main challenge towards late field life. For such challenging condition, pre-planning with multiple Autonomous Inflow Control Device (AICD) valve placement scenarios across the horizontal sections were analyzed using integration of reservoir and well models for valves optimization process to achieve well's target production and reserves by the end of PSC. Specific drawdown and production targets were set as critical design limits in managing sanding and erosional risks while still achieving production target. Ultimately, these models provided both instantaneous and long-term forecasts of AICD impact on the wells’ performance – key factors in the final design. The workflow presented in this project synergized scope of multi-domain from subsurface, completion and drilling. This case study demonstrates the value of detailed design steps on AICD placement across horizontal segments and optimizations based on actual open-hole logging interpretation, mainly – permeability, saturation and vertical stand-offs from gas-oil and oil-water contacts. The horizontal wells drilled are susceptible to "heel-toe" effect, resulting in dominant production in the heel section while the toe section contributes less, subsequently inducing gas coning at the heel. XXYY reservoir is also sand prone and requires sand control. For these reasons, all 4 wells are designed to be completed with Open Hole Stand Alone Screen (OHSAS) with the use of AICD to balance production withdrawal across the horizontal segments and provide GOR control. The four (4) wells penetrated 30-60ft-TVD of oil column with 10-15ft-TVD vertical stand-offs from gas-oil contact (GOC) to maintain a 2/3 column ratio from oil-water contact. Given these marginal stand-offs to GOC, integration of AICD sensitivities workflow were performed on-the-fly to analyze instantaneous and time-stepped oil and GOR rates allowing the team to achieve required production sustenance. The installations of optimized AICD have resulted in successful GOR control below 6 Mscf/stb targeted, resulting in delivering higher instantaneous production rates against planned of 4,600bopd. The success of AICD optimizations integrated with OHSAS completion, reservoir mapping and petrophysical evaluation have been proven as ultimate solution to deliver the wells oil production for a brown field rejuvenation project. The pre-drill and post-drill results calibrated to actual well tests are compared for further sensitivity analysis, to be used in the continuous improvement of production management strategies in the field.
Wells 1A, 2A, 3A & 4A are designed as four (4) horizontal oil producers to maximize the oil recovery from the XXYY heterogenous sandstone reservoir in Offshore Malaysia. The reservoir has been producing since 1975 on natural depletion before gas injection (1994) and water injection (2019-2022) were introduced. XXYY reservoir is expected to have wide permeabilities ranges from as low as 1-mD to 4-D and high uncertainty of gas-oil contacts from recent saturation logging acquisition. Coupled with the complex reservoir nature of massive gas cap and thinning oil rim observed between 30-50ft-TVD, historical production of oil with optimum GOR in XXYY reservoir remained the main challenge towards late field life. For such challenging condition, pre-planning with multiple Autonomous Inflow Control Device (AICD) valve placement scenarios across the horizontal sections were analyzed using integration of reservoir and well models for valves optimization process to achieve well's target production and reserves by the end of PSC. Specific drawdown and production targets were set as critical design limits in managing sanding and erosional risks while still achieving production target. Ultimately, these models provided both instantaneous and long-term forecasts of AICD impact on the wells’ performance – key factors in the final design. The workflow presented in this project synergized scope of multi-domain from subsurface, completion and drilling. This case study demonstrates the value of detailed design steps on AICD placement across horizontal segments and optimizations based on actual open-hole logging interpretation, mainly – permeability, saturation and vertical stand-offs from gas-oil and oil-water contacts. The horizontal wells drilled are susceptible to "heel-toe" effect, resulting in dominant production in the heel section while the toe section contributes less, subsequently inducing gas coning at the heel. XXYY reservoir is also sand prone and requires sand control. For these reasons, all 4 wells are designed to be completed with Open Hole Stand Alone Screen (OHSAS) with the use of AICD to balance production withdrawal across the horizontal segments and provide GOR control. The four (4) wells penetrated 30-60ft-TVD of oil column with 10-15ft-TVD vertical stand-offs from gas-oil contact (GOC) to maintain a 2/3 column ratio from oil-water contact. Given these marginal stand-offs to GOC, integration of AICD sensitivities workflow were performed on-the-fly to analyze instantaneous and time-stepped oil and GOR rates allowing the team to achieve required production sustenance. The installations of optimized AICD have resulted in successful GOR control below 6 Mscf/stb targeted, resulting in delivering higher instantaneous production rates against planned of 4,600bopd. The success of AICD optimizations integrated with OHSAS completion, reservoir mapping and petrophysical evaluation have been proven as ultimate solution to deliver the wells oil production for a brown field rejuvenation project. The pre-drill and post-drill results calibrated to actual well tests are compared for further sensitivity analysis, to be used in the continuous improvement of production management strategies in the field.
The aim of this paper is to demonstrate how the adoption of autonomous inflow control (AICD) can lower water production and CO2 intensity in a field situated on the Norwegian continental shelf. The study outlines the process starting from device qualification and testing in a flow loop, followed by evaluation through modelling and reservoir simulations, then well planning to optimize AICD implementation, and finally the measurement of the effect in several wells. Breidablikk is an oilfield located on the Norwegian continental shelf that commenced oil production in October 2023. The oil reserves are at a depth of about 1750 meters, forming a thin layer that sits atop a strong water aquifer. Prior to production, a range of AICD solutions aimed at water reduction were evaluated, including qualification, and testing of the devices in a flow loop to obtain their flow performance data. This data was subsequently used as input in multiple reservoir simulations to determine the optimal distribution of AICDs in the wells. The wells are closely monitored to confirm that the expected AICD behavior has been achieved. The Breidablikk wells consist of long horizontal sections, both single and multilaterals, with lengths of up to 1600 meters. They are equipped with screens, various inflow control devices, blank sections, and swell packers. Following implementation and production start-up, measured flow rates and pressures are compared against the expected AICD performance. The lower completion design is optimized using a steady-state well simulator and the use of a dynamic reservoir simulator to provide expected production profiles. During the stepwise clean-up of the wells and branches, differential pressure and oil rates are used to measure well clean-up and AICD efficiency. The pressure drop across the AICDs is determined based on down hole pressure, plotted versus initial well test rates, and is consistent with laboratory tests under similar conditions. Chemical tracers have also been used to verify clean-up during flow performance evaluation. Based on the successful implementation, there is a good basis for planning and optimizing use of AICDs in future wells at Breidablikk. The reservoir drainage strategy for Breidablikk depends upon implementing artificial lift and utilizing the well designs mentioned earlier. Production of the wells at minimal gas lift rates, in combination with on/off well production, allows for higher NPV and recovery to be attained throughout the anticipated field lifetime. To ensure a successful implementation, step rate tests are performed to affirm the AICD flow characteristics determined through lab testing and simulations.
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