Integration of Petrophysical Analysis and Elastic Log Properties as an Input to Optimize Development Wells Target in Unique Globigerina Limestone Gas Reservoir in Madura Strait

Abstract

The Madura Strait PSC is located in the southern part of North East Java Basin with biogenic gas from Globigerina limestone Pliocene Mundu and Selorejo sequence as main target. At early stage of field development, understanding and knowledge about petrophysical and elastic properties of reservoir rock quality is required and very important. The petrophysical analysis provide properties such as clay volume, porosity, permeability, water saturation and mineral volume to separate reservoir and non-reservoir zone. The elastic rock properties such as acoustic impedance (AI), shear impedance (SI), velocity ratio (Vp/Vs), Poisson’s ratio (σ) were generated to identify clay zone, gas and non-gas also focused to distinguish reservoir rock quality inside gas zone as an effective reservoir characterization. This research is done by utilize core data, quad combo logs from eleven wells and shear velocity from eight wells. The purpose of this research is to optimize development well target in Globigerina limestone gas reservoir, which have good to best reservoir rock quality shown with high porosity and permeability, low clay volume and water saturation. Results from this research indicate that lime mud matrix have significant impact in the reservoir rock quality. Meanwhile, gas saturation can affect the elastic properties due to this high gas saturation can decrease compressional velocity (Vp) value. Finally, the integration of petrophysical result and combination of elastic properties implementation can help in distinguishing the best reservoir rock quality, which contains gas that should be penetrated by the development wells.