Reservoir Simulation Challenges for Modeling a Thin Volatile Oil Rim With Large Gas Cap in the Poleng Field, Kujung-I Oil Reservoir, East Java Basin, Indonesia

Forrest, James K.; Sukmana, Ade; Suhana, Widayat; Asjhari, Imron

doi:10.2118/93137-ms

Cited by 4 publications

References 1 publication

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Reliable Characterization and Modeling of the Capillary Transition Zone and Flow dynamics in the Oil Rim Reservoirs

et al. 2011

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The oil rim reservoirs are referred to the reservoirs with limited oil column underlain with aquifer and overlain by a gas cap. In such reservoirs, the whole oil column can be in the capillary transition zone with a complex flow dynamics. In some cases, oil might have been displaced by imbibition process over geological time during the fluid migration history following the initial primary drainage. Understanding the capillary transition zone, displaced oil zone, saturation modeling, mobile oil distribution and flow dynamics can influence the resource estimation, field development planning and ultimate recovery. In this paper, we present an extensive review on the concept of the transition zone characterization and the current limitations and challenges in modeling static and dynamic properties in oil rim reservoirs. Various actual field data and examples are presented to better understand the flow characteristics in capillary transition zone. To perform the study, we utilize sector modeling from real oil rim fields with displaced oil zone, the actual drainage and imbibition SCAL measurements, and the historical field performance data. Modeling approaches based on sole drainage and sole imbibition for initialization, imbibition and hysteresis impact on the flow dynamics and residual oil saturation (Sor) dependent to the initial oil saturation (Soi) have been investigated. The study show that the sole drainage based approaches could underestimate the potential of the transition zone, which can make the project less commercially attractive. This method can lead to significant errors in residual oil saturation and inevitably unrealistic history match assumptions. The resulted model could be very mis-leading in the production forecasting. It is shown that proper description of representative relative permeability and capillary pressure data and residual/initial oil saturation dependency will lead to a more realistic history matched model. This could play a major role in the field performance predictions including the value of the tertiary oil recovery, in particular, for heterogeneous reservoirs.

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Reliable Characterization and Modeling of the Capillary Transition Zone and Flow dynamics in the Oil Rim Reservoirs

et al. 2011

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Continuous Incremental Reserves in an Oil Rim Marginal Field Development through Integrated Technical Initiatives and Technology Advancements

Masoudi

Karkooti

Chan

et al. 2012

SPE Annual Technical Conference and Exhibition

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Oil rim reservoirs are commonly marginal reserves with challenging drive-systems with high development cost and, therefore, are commercially less attractive. Development evaluation of such complex fields with the conventional methodologies and technologies may result in unsuccessful scenarios. The studied field, located in offshore Peninsula Malaysia, is a marginal oil rim reservoir with the oil column less than 42 ft with limited oil-in-place. The field was initially evaluated as a challenging development and a non-commercial asset. However, the integration of various technical initiatives and applying new interpretive techniques turned the field into an attractive asset and reserves have been continuously upgraded since the field development started. The field was undergone proactive phasing development and reservoir management with a fit-for-purpose monitoring plan. The development strategy with long horizontal wells (i.e., up to 2 km) and smart completion with inflow control devices was matured through the development phasing and well-by-well performance evaluation. Various tracer applications with the PLT campaign in the long horizontal wells pre/post water-breakthrough (WBT) were used to justify the long horizontal wells. Well placements relative to contact were progressively improved allowing the delay in WBT and increasing the RF. Production rate, draw-down and GI/GP were continuously optimized pre/post water/gas break-through. Simulation model incorporated robust modeling of flow dynamics of the oil intervals in the capillary transition zone and long horizontal wells with smart completion modeling using the segmented well approach. The applied development strategies together with the proactive reservoir management made the field development as a record successful case in Malaysia. The recovery factor progressively increased from earlier 16% to 35% presently. In this paper, suggested workflow, guidelines and key tasks with the field data and the results are presented and discussed for the studied field.

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Rejuvenation of N2 Layer Reservoir with Shift Paradigm from Gas Reservoir into Oil Reservoir: A Case Study from Benuang Structure, South Sumatera

Abdillah,

Ardianto,

Dwiokta

et al. 2024

Day 2 Wed, May 08, 2024

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This paper focuses on developing a substantial oil reservoir in South Sumatra, Indonesia, characterized by a large gas cap and a bottom water aquifer. The reservoir comprises thick, clean sandstone from the Miocene Talang Akar Formation, deposited in a transitional estuarine complex with good porosity and lateral continuity due to an accreted channel complex. Initial production was gas-dominated, leading to its classification as a non-potential reservoir with a recovery factor (RF) of up to 79%. The recent success in infill drilling has resulted in nearly 4000 BOPD from the N2 layer, revealing the ongoing potential for oil reserves. The shift from gas to oil production in the reservoir is an intriguing phenomenon. To understand this shift, static and dynamic data from the latest infill drilling, along with current saturation logs from existing wells, are evaluated. This comprehensive analysis forms the basis for constructing a reservoir model. The model is expected to describe the reservoir's conditions from its initial state to the current condition and assess the potential for incremental production. The comprehensive reservoir model estimates gas in place at 41 BSCF with an RF of 79%, based on cumulative production of 33 BSCF. The estimated oil in place is 11 MMSTB with the current RF at only 10%, from 1.1 MMSTB. The results of the recent study present opportunities for further development in the N2 layer using clustering infill drilling, workovers, and pressure maintenance to optimize oil production. This is estimated to have a potential additional oil production of 3.9 MMSTB, representing a ‘New Life’ for the N2 layer by shifting the paradigm from developing the gas reservoir to developing the oil reservoir. The evaluation of the N2 layer can change the paradigm for gas reservoirs with oil rims. While the common rule in the oil and gas industry is to produce oil first to optimize oil recovery, the case of the N2 layer challenges this norm. Despite the reservoir producing a large volume of gas, the oil potential remains high and can be developed by considering various reservoir parameters, as explained in this paper.

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Reservoir Simulation Challenges for Modeling a Thin Volatile Oil Rim With Large Gas Cap in the Poleng Field, Kujung-I Oil Reservoir, East Java Basin, Indonesia

Cited by 4 publications

References 1 publication

Reliable Characterization and Modeling of the Capillary Transition Zone and Flow dynamics in the Oil Rim Reservoirs

Reliable Characterization and Modeling of the Capillary Transition Zone and Flow dynamics in the Oil Rim Reservoirs

Continuous Incremental Reserves in an Oil Rim Marginal Field Development through Integrated Technical Initiatives and Technology Advancements

Rejuvenation of N2 Layer Reservoir with Shift Paradigm from Gas Reservoir into Oil Reservoir: A Case Study from Benuang Structure, South Sumatera

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