Production Optimization through Pressure Transient Analysis

Intelligent field completions have seen more frequent deployment in the oil and gas industry in recent times. This is most likely due to the benefits that have been observed from real-time data acquisition, surveillance and optimization based on analysis of data gathered. With continuous acquisition of real-time data, analysis of the transient pressure and rate data can be used to understand changes in reservoir and well performance over time. The aim of this paper is to show how the evolution of parameters obtained from pressure transient analysis can be used to optimize well and reservoir performance. Key parameters obtained from pressure transient analysis (PTA) are permeability, skin, reservoir pressure and information on boundaries depending on shut-in duration. Analyses are performed for all shut-ins of the completion, both planned shut-ins and unplanned shut-ins (emergency shutdowns - ESDs). The results of all these analyses are catalogued to provide an historical surveillance data which, when trended, can provide insight into the near-wellbore performance of a completion as well as the reservoir. This paper demonstrates how Pressure Transient Analysis of real-time data was used in the Agbami Field to optimize production from the field. Two case studies are presented where analysis of transient pressure data was used to identify water injection front movement in a waterflooded reservoir and increasing near-wellbore damage due to fines migration. The results were used to optimize injection into a waterflooded reservoir to achieve a balance between maintaining reservoir pressure and optimizing voidage. In the case of continually increasing skin, the completion was stimulated with production increasing by a factor of 15.