Sweet Spot Identification and Optimum Well Planning: An Integrated Workflow to Improve the Sweep in a Sector of Giant Carbonate Mature Oil Reservoir

Abstract

This study illustrates a comprehensive-integrated approach to identify the potential locations for future development in a sector area of a giant carbonate mature oil reservoir. The approach uses various data from several sources including reservoir surveillance, production performance, geological interpretation and numerical simulation and cohesively combines them to yield an informed decision to assess field development and management. The study area is under peripheral waterflood for more than fifty years and dominated by heterogeneity related to fracture corridors, high permeable zone, and reservoir zonation. These features leads to a preferential and uneven propagation of water flow which results in un-swept oil bearing spots using the existing wells lay-out and configuration. The reservoir management team has developed an integrated workflow to address these challenges by using several reservoir engineering methods and models including Water Encroachment, Reservoir Opportunity index, Fractional Flow Calculation, Remaining Volumetric and Water Flow Paths. The designed workflow consists of creating derived attributes that describe these models and filter the sector area to define the sweet spots. The selection and prioritization of the defined sweet spots are supported by available reservoir surveillance and production data. However, the scarcity of reservoir surveillance and production data in some areas of the sector, motivated reservoir management team to stretch the limits by capitalizing on gas wells penetrating the shallower oil reservoirs. The open-hole logs of these wells recorded thicker oil column than the preestimated column using the existing surveillance data. As a result of these efforts, a development plan was designed in order to ensure reserves depletion in the identified sweet spots by drilling new wells or sidetracking the existing wells. Despite the level of maturity, simulation forecasts indicate that the area of interest has lot of potential to sustain a high production rate.