Best Practice of Lower Completion Screening Technique for a Marginal Oil Field – Case Study from Onshore UAE

Abstract

Lower completion in openhole horizontal well is known to improve oil sweep, aid water control and water shut-off in carbonate reservoir. In a marginal oil field of onshore Abu Dhabi, lower completion is an important role to achieve the long-term recovery and production sustainability. The lower completion candidate selection process for marginal field is unique due to economic indicators are stringent than large field's application. In this paper, we will present an integrated approach of lower completion screening to solve both technical challenges and economic consideration in a green marginal oil field. We incorporated a multi-domain screening approach where findings from comprehensive set of data and analysis are integrated. Multi-level analysis was performed to obtain a weighting factor or indicator for lower completion need per well. The evaluation includes production history, logs, borehole image, reservoir compartmentalization analysis, well trajectory, drilling losses history, surveillance such as pressure transient analysis and production logging and other data. One of the considerations of lower completion is to remove accessibility issue. Indicator was gathered based on historical coil tubing accessibility evaluation and review of well with high dogleg trajectory. Lower completion need for water control is evaluated through multiple analysis such as water conformance analysis and evaluation of preferential communication between producer and injector. The analysis is complemented with study of oil and water influx distribution based on production logging, permeability-thickness log, borehole image interpretation, drilling losses history, and pressure transient analysis. Indicator were also collected per well for potential influx mitigation and water shut off need due to natural fractures and fault. Additionally, reservoir compartmentalization analysis was also performed to identify if horizontal wells are located at multiple compartments and can be benefiting from lower completion. Around 20 wells were included during the study. A standardized matrix scoring and ranking were generated. From the screening result, 12 wells have been selected as best candidates for lower completion deployment. Few wells were selected due to well accessibility issues and trajectory challenges and remaining wells selected due to non-conformance water breakthrough and or due to strong preferential communication with water injector. That candidate was further studied through numerical simulation and subsequently economic indicator were generated to support the decision making and implementation priority. From this study, 3 Pilot implementation of inflow control device complemented with sliding sleeve door mechanism are due for implementation in the near term. In a green field, lower completion candidate screening is a continuous process and will need to be updated when new findings or surveillance are obtained. It may also be adjusted along with evolution of field development plan. The screening practice presented in this paper may be adopted by other asset for an effective lower completion screening study.