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

Abstract

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.

Challenges and Rewards in the Resource Evaluation and Flow Modeling of Transition Zone

“…Differentiation between capillary and apparent transition zones and reliable understanding of the volumetric assessment based on determination of their boundaries play a major role in project economy and the success of field development [1,2,3] . The failure of correct identification of CTZ leads to by-passing oil-rich footage of a producible zone or on the contrary, early breakthrough of water or miss-guided infill wells that could pave the way to economic failure of the project.…”

“…The characterization of the flow dynamics and modelling methodologies were detailed together with an oil rim case study for the capillary transition zone (CTZ) in previous publications [2,3] . In summary, the end points and curvature of the relative permeability curve both for the water and oil may need to be modified based on the height above the FWL.…”

“…As mentioned earlier, details of a development project from a CTZ in an oil rim reservoir based on the above proposed methodology was elaborated in the previous paper as a case study for this approach [3] . Two more case studies of apparent transition zone (ATZ) from turbidite laminated shale/sand and thin bed reservoirs are discussed in the following sections.…”