The acquisition of high quality reservoir information in exploration campaigns is a continuous challenge in today's operations. The operational risks, time, cost, environmental concerns and reservoirs complexities are several important factors to be considered in reservoir characterization planning. Key reservoir information includes fluid types and composition, horizontal permeability, vertical permeability, damage skin, radius of investigation and reservoir pressure.This work presents the reservoir evaluation done in the basement with the mobility range of 0.01 to 0.09 mD/cP in an offshore Malaysia oil field. An early and quick identification of hydrocarbon prospect was required for appraisal wells planning. The expected low mobility in basement complicates the exploration data acquisition. Conventional reservoir fluid characterization through bottom hole sampling and PVT lab analysis is proven to be ineffective due to the long waiting time before the results are available. Full scale DST on the other hands offers higher operational complexity and cost for reservoir parameters determination.As an alternative, the wireline formation tester dual packer module was deployed to perform a DST like testing known as interval pressure transient test (IPTT). At the interval of interests with the presence of hydrocarbon, the dual packer module offers selectively straddling reservoir sections to provide the capability to conduct controlled local production and interference for reservoir parameters estimation through pressure transient analysis. Downhole fluid analysis was performed to provide the reservoir fluid properties input. By providing larger flow area also, dual packer module enables the reservoir characterization in the low mobility intervals through downhole fluid analysis and IPTT techniques. The examples of IPTT applications in oil reservoirs and the analysis methodology will be presented in this paper.

Reservoir fluid composition and reservoir parameters characterization are fundamental for the accurate reservoir description during exploration phase and successful reservoir management in gas field development planning. Key reservoir fluid parameters namely hydrocarbon composition and Carbon Dioxide (CO2) are essential input to comprehensive production and reservoir engineering studies.The paper presents the exploration work done through three gas wells campaign in two main Malaysia basins. The formation is mainly thinly laminated sand-shale beds and the main objective for the operator is to acquire an early and quick identification of hydrocarbon prospect for appraisal wells planning. With that, compared to conventional PVT lab analysis which can easily take weeks to months to complete and full scale DST that offers higher operational complexity and cost, downhole fluid analysis was deployed.Downhole fluid analysis has successfully identified the reservoir fluid composition and properties for different fluid types. In this offshore Malaysia basin, high CO 2 content was not expected geologically, high CO 2 was measured in several sands of interest and this early identification on non-hydrocarbon prospect avoids unnecessary cost, time and operational risks. This work presents the successful downhole reservoir fluid identification in mobility range of 23.2 to as high as 5263.8 md/cP. The methodology, applications and suggested best practices applied throughout the campaign are presented in this paper. TX 75083-3836, U.S.A., fax +1-972-952-9435

Reservoir rock properties, fluids' type and pressure are fundamental parameters for the successful reservoir management in field development planning. Key reservoir parameters are namely horizontal permeability, vertical permeability, damage skin, radius of investigation and reservoir pressure. Together with the reservoir fluid properties, they form critical input to comprehensive production and reservoir engineering studies. Exploration work done through a 3 wells campaign in three main gas fields offshore Malaysia is presented in this paper. The main objective for the operator is to acquire an early and quick identification of hydrocarbon prospects for appraisal wells' planning. Compared to the conventional full scale DST, the combination of Downhole fluid analysis and interval pressure transient test (IPTT) by wireline formation tester were deployed to achieve these objectives. This paper illustrates the successful downhole reservoir fluid identification and formation testing in the reservoirs with the mobility range of 365 to 3020 md/cP. At the interval of interests with the presence of hydrocarbon, dual packer formation tester module offers selectively straddling reservoir sections to provide the capability to conduct controlled local production and interference for reservoir parameters estimation. The methodology, applications and suggested best practices applied throughout the campaign are presented in this paper.

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