FDP Optimization with Techno-Economic Viable Infills and Their Impact in Water/Miscible WAG Injection in Heterogeneous Reservoir

Abstract

Summary An extensive study was conducted to optimize the field development plan (FDP) with infill wells in water and miscible water-alternating-gas (WAG) displacement processes for high and moderately heterogeneous areas of stratified carbonate reservoir. This reservoir is complex heterogeneities with numerous fractures, high perm steaks, multiple sub-layers with variable permeability and intrabed communication with other reservoirs. Within this reservoir, the wells have dual completion through short/ long strings. It is observed that injected water /gas is flowing through high permeability layers and leaving a lot of oil in un-swept area. Therefore, in order to sustain target oil production and improve recovery, this reservoir is currently undergoing re-development with different innovations including maximum reservoir contact (MRC) wells with line drive injection pattern drilled from different artificial islands, gas lift, infill wells, different tubing size strings, different types of well completions (limited entry liner –LEL, pre perforated liner- PPL, inflow control devices- ICD and inflow control valve- ICV) and appropriate EOR technology. This article presents analytical models and a step by step work flow to optimized FDP for optimum tubing size, well spacing, vertical well placement, well length to reduce the gap between toe to heel of two wells, techno-economic viable number of infill wells and their location (vertical and areal) for maximizing the recovery and maintain the longer plateau at target production rate. An FDP is formulated with optimum tubing size, well spacing, well length, vertical well location and techno-economic viable infills in water / miscible WAG flooding for a highly heterogeneous complex stratified reservoir.