Well, Reservoir and Facilities Management (WRFM) and Surveillance Planning in a Multi-Stacked Mature Oil and Gas Field in Baram Delta

SPE Asia Pacific Oil and Gas Conference and Exhibition

Dan

et al. 2018

Managing an oil rim type reservoir has constantly been a great challenge and understanding the oil rim movement has remained as one of the main subsurface uncertainties. Prudent reservoir management through an active reservoir, well and facilities management (RWFM) plan is key to realizing the uncertainties, optimizing production and reserves of brownfields. Monitoring the oil rim through cased-hole reservoir saturation logging has been identified as a de-risking method, planned and executed for two consecutive years in the field to minimize the oil rim uncertainty. The field studied is one of the brownfields in offshore Sarawak, Malaysia, which has been on production for more than 40 years. Results acquired from the cased-hole logs have triggered the need to optimize the location of an infill oil producer planned in the Field Development Plan. The cased-hole results indicated that the original oil target in the N reservoir had mostly been swept by water. Through thorough studies and modeling, an opportunity to the western flank in M reservoir, located close to a proposed workover well, was suggested. Furthermore, latest input on the proposed workover well and facilities health check suggested the workover candidate was not favourable due to its location on an aging single well monopod structure with complex well mechanical problems. Thus, the planned infill oil producer was recommended to replace the workover well and recover the reserves. Integrated studies incorporated cased-hole results with reservoir modeling indicated that the new infill location would yield a total of 5.7MMSTB reserves with initial production rate of 1215BOPD. In addition, through integration of a multi-disciplinary team, revision to the infill location was timely and the infill was also accelerated from Phase II to Phase I of the development plan as a rig filler for cost optimization. Well test result successfully validated the reservoir productivity of 1238BOPD with no water production. This paper presents the integrated subsurface and surface solutions and criticality of proactive data acquisition, field monitoring and collaborative team work strategies to maximize the recovery from a brownfield.

Successful Infill Realized through Prudent Brownfield Oil Rim Reservoir Management, Offshore Malaysia

Khalid

SPE Asia Pacific Oil and Gas Conference and Exhibition

Dan

et al. 2018

Value Creation from the Reservoir, Well and Facilities Management RWFM Planning in Multi-Stacked Mature Oil Rim Reservoirs, Offshore Sarawak Malaysia

SPE Annual Technical Conference and Exhibition

Elharith

et al. 2019

Managing a 47-year brownfield, offshore Sarawak, with thin remaining oil rims has been a great challenge. The dynamic oil rim movement has remained as a key subsurface uncertainty especially with the commencing of redevelopment project. A Reservoir, Well and Facilities Management (RWFM) plan was detailed out to further optimize the development decisions. This paper is a continuation from SPE-174638-MS and outlines the outcome of the RWFM plan and the results’ impact towards the development decisions, such as infill well placement and gas/water injection scheme optimization. Key decisions impact by the RWFM findings are highlighted. One of the RWFM plans is oil rim monitoring through saturation logging to locate the current gas-oil contact (GOC) and oil-water contact (OWC). Cased-hole saturation logs were acquired at the identified observation-wells across the reservoir to map time-lapse oil rim movement and its thickness distribution. Pressure monitoring with regular static pressure gradient surveys (SGS) as well as production data, helped to understand the balance of aquifer strength between the Eastern and Western flanks. Data acquisition opportunity during infill drilling were also fully utilized to collect more solid evidences on oil rim positions, where extensive data acquisition program, including conventional open-hole log, wireline pressure test, formation pressure while drilling (FPWD) and reservoir mapping-while-drilling, were implemented. The timely collection, analysis and assimilation of data helped the team to re-strategize the development / reservoir management plans, through the following major activities: Re-strategizing water and gas injection plan to balance back oil rim between the Eastern and Western flanks, through deferment of drilling water injectors, optimization of water and gas injectors location and completion strategies due to stronger aquifer encroachment from east and south east.Optimizing infill wells drainage points where 2 wells were relocated based on cased-hole logs, as the first well original location was swept and the second well was successfully navigated through the oil rim using reservoir mapping-while-drilling techniques coupled with cased-hole log results. This resulted in securing an oil gain of 4000 BOPD from these 2 wells.Optimizing infill wells location and planning an additional infill well with potential additional oil gain of approximately 2000 BOPD.The understanding of current contact and aquifer strength from the surveillance data assisted in identifying fit-for-purpose technology for the new wells such as the application of viscosity-based autonomous inflow control device which assisted in placing the well closer to GOC due to the observed rapid rising of water table, this will help sustaining the well life. This paper highlights the importance of data integration from geological knowledge, production history, reservoir understanding and monitoring through regular SGS and time-lapse cased-hole saturation logging, coupled with extensive data acquisition during infill drilling. By analyzing and integrating the acquired data, project team can then confidently re-strategize and successfully execute the complex mature oil-rim brownfield redevelopment.

Successful Monetisation of an Extremely Thin Oil Rim and Slanted Contact Reservoir, Offshore Malaysia, through Emerging Technologies and Innovative Concepts

SPE/IATMI Asia Pacific Oil &Amp; Gas Conference and Exhibition

Dan

Tusimin

et al. 2020

The scope of the paper is to share a case study of a successful horizontal well completed within an extremely thin oil rim of ~10ft with bottom water. This paper highlights the differentiating activities undertaken to deliver the well despite the challenges of extremely thin oil rim, strong water drive and uneven current fluid contacts. Prior to drilling this well, attempt was made to mitigate the uncertainty regarding the current gas-oil contact (GOC) and oil-water contact (OWC) by carrying out cased-hole logging in some of the adjacent wells, and re-sequencing and re-optimizing the location of two of the wells targeting the reservoirs below. This obviated the need for the pilot hole and thereby resulted in a cost saving of ~USD 1Million. Furthermore, the dynamic simulation model was updated to create a fit-for-purpose model with the latest OWC and GOC, so as to be able to test various trajectories. While drilling, the well was drilled with real-time reservoir mapping-while-drilling technology and integrated with real-time reservoir characterization, fluid typing and trajectory modification, while maintaining Dog Leg Severity (DLS) below 3 deg/100ft for the ease of completion run. Completion was then optimized with viscosity-based inflow control orifices. Post drilling, dynamic and well models were calibrated to the actual results to determine optimum production rate for the well life. The horizontal well was successfully navigated and optimally placed in the extremely thin oil column. Tilted contacts were encountered in the targeted subunits where actual current contacts came in ~20ft shallower at heel and ~10ft deeper at toe compared to prognosis. Consequently, the heel landed at a 5ft stand-off from water, and the toe landed 18ft stand-off from water and 6ft stand-off from gas. The well was successfully unloaded and tested at a controlled oil rate of 2887 bopd, 50% higher than planned target. This paper presents the entire process from well planning until well production tie-in. This was achieved through the integration of subsurface understanding with the utilization of the appropriate technology. Finally, the management's trust in the capability of the team members ensured deliverability of the target production rate and the consequent booked reserves.