Integrated Field Study Involving Downhole Fluid Analyzer DFA for Reservoir Connectivity in Thin Complex Lithology Formation: Case Study from Oman

摘要

Early information about reservoir fluid complexity, dynamic behavior, and reservoir connectivity isrncrucial for development planning and production optimization of new plays. Such impact is manifestedrnin three main areas: (1) reservoir presence and connectivity to understand the extent of the play (2)rnreservoir fluid variation to understand the charge history and devise production strategy (3) completionrnoptimization in exploration wells to maximize early production.rnPetroleum Development of Oman pursued an ambitious exploration campaign firstly consisting of 8rnwells targeting a shallow, thin, complex lithology formation to better understand a new play, especiallyrnfrom reservoir extension and connectivity viewpoints. In addition to advanced formation evaluationrnlogging consisting of elemental spectroscopy and nuclear magnetic resonance, an advanced DownholernFluid Analyzer (DFA) was deployed with Wireline Formation Testers (FT) aimed to obtain formationrnpressure and fluid samples. The fluid scanning using in-situ fluid analysis was also performed to obtainrnreservoir fluid information in real time and at reservoir condition. In addition, Interval Pressure TransientrnTests (IPTT) was conducted to evaluate permeability of each well.rnThis paper provides the workflow of using the DFA and laboratory data for full field development. Thisrnwill include discussion of DFA data such as asphaltene, fluid composition, Gas-Oil-Ratio (GOR), density,rnviscosity, and fluorescence yield to help draw a full picture towards reservoir connectivity.rnHaving detailed fluid properties data available in real time allows to optimize the completion decisionsrn(pump selection as one example) in order to maximize early production while allowing longer termrnreservoir management planning. This paper also discusses the use of in-situ fluid viscosity and pressurerntransient data to estimate zone permeability during the FT operation, which will later be compared tornactual well test data. Results show a good comparison and provide comfort to use FT pressure transientrndata to evaluate zone permeability at early stage of the operation.rnThe DFA data from the first 4 wells suggested the presence of subtle but distinct fluid differences inrnterms of composition, oil color, and fluorescence yields. This DFA data was then supported by full PVTrnlaboratory results. The differences in fluids will be examined in more details. This paper will present an effective workflow to integrate pressure, DFA, and PVT data to understand reservoir connectivity issuernin this newly discovered formation. In addition, the DFA color gradient model was then used to helprnsupporting other available information.