Validation and Analysis of Past PVT Studies from a Complex and Mature Offshore Asset in Trinidad

Abstract

In 2005, NGC, Petrotrin and Repsol E&P T&T Ltd. as joint venture partners, acquired the TSP asset with Repsol as the operator. The three fields, Teak, Samaan and Poui, have been in production for over 40 years and are highly complex, extremely compartmentalized and consist of over 10 different sands and reservoirs. Over 100 PVT files for the three fields are available; most of which were done in the 1970's by different labs using different protocols and procedures. All files were handed over in paper form which needed digitization as well as validation. Valid PVT data provides vital information for the characterization of reservoir fluids. The establishment of fluids' physical and PVT properties help determine in situ and stock tank volumes, strategies for production, flow assurance issues for facilities design and provides guidelines for effective and efficient reservoir management throughout the life of the asset. Numerous techniques exist for assessing and evaluating the quality of PVT data. This paper will describe the best practices used to validate TSP PVT data, such as the material balance tests and the Y-function linearity tests as well as the applications of the validated data through examples and case studies. Some of which include the development of trends which can be extrapolated for use in new prospects, infill and developmental drilling. Additional benefits include the recognition of flow assurance issues such as wax and sulphur compounds and the sampling and design of relevant PVT experiments for new wells. Production history combined with valid PVT data provides a powerful tool to help in the prediction of expected fluid types and fluid behaviour as pressure changes in planned new wells. It also provides additional technical support for which improvements to the fluid sampling program can be made to acquire the most representative fluid samples from the reservoir.