Operational Procedures and Applications of a Wireline Formation Tester to Accurately Characterise the Gas Composition of Stacked Multiple Pools in the North Malay Basin.

摘要

An accurate knowledge of reservoir fluid composition,rnspecifically the concentration of hydrocarbon gases and noncombustiblerngases such as carbon dioxide, is a key factor in therncommercial assessment of upstream gas projects at thernexploration and field appraisal drilling stages, and inrndevelopment planning.rnThe precise measurement of reservoir fluid compositionrnrequires the acquisition of a representative sample of formationrnfluid, free of drilling fluids and other contaminants.rnTraditionally, Drill Stem Tests have offered the most reliablernmethod to obtain this information. However, the cost of thisrnmethod limits its application in gas accumulations comprisedrnof multiple, stacked, separate pools where the individualrnreservoir fluid compositions need to be well known.rnCarigali Triton Operating Company Sdn. Bhd. (CTOC),rnOperator of Block A-18, JDA on behalf of its Shareholders,rnPetronas Carigali (JDA) Sdn. Bhd., Triton Oil Company ofrnThailand (JDA) Limited and Triton Oil Company of ThailandrnInc., is now consistently able to acquire reservoir fluid samplesrnwhich are confirmed by on-site advanced chromatography, andrncalibrated by Drill Stem Tests to be fully representative of insiturnnative reservoir fluid compositions. This has beenrnachieved through the use of a wireline formation tester with anrnenhanced pump-out capability and a downhole fluid analyser,rntogether with the development and implementation of keyrnoperational procedures for performing the logging operation.rnThe accuracy and reliability of the technique has beenrnproven and refined over the sixteen-well exploration programrnin Block A-18, where downhole conditions can be hostile, andrntool operating time has exceeded 40 hours. This technique hasrnenabled the Operator to obtain specific and accuraterninformation on the fluid composition of individual reservoirs,rnand therefore reduce appraisal and development uncertainties,rnin a fraction of the time which would have been needed forrnconventional Drill Stem Testing, and at a fraction of the cost.rnThis paper describes the tool, together with the techniquesrnthat have been implemented at the well site to obtainrnrepresentative reservoir fluid samples in an efficient and costeffectivernmanner. Wireline Formation Tester Drill Stem Testrnresults from the Block A-18 exploration and appraisal programrnto date are compared to demonstrate the accuracy andrnreliability of the methods employed.