Comprehensive Multipore System Analysis for a Better Understanding of Metasediments Reservoir Deliverability:a Case Study from the South Malay Basin Offshore Peninsular,Malaysia

摘要

Fractured basements are one of the more complex types of reservoirs for drilling,assessment,develop- ment,and production enhancement.While they represent some of the largest and most productive reservoirs,they decline rapidly and are prone to undesirable fluids breakthrough.When characterizing fractured basements to better estimate reservoir capacity and deliverability,it is important to understand the role that matrix porosity and fracture network play in reservoir performance.This is especially true when the reservoir has been subjected to a variable metamorphic grade during different tectonic episodes, in addition to localized contact metamorphism by intrusions. Matrix porosity can be estimated from electric wireline and logging/measuring while drilling tools. However,for better estimation and to help minimize uncertainty,identifying the rock-forming minerals using elemental analysis on core or ditch cuttings is essential.The composition of the metasediment can be used to identify the original sedimentary rock,even where it has been subject to high-grade metamorphism and intense deformation.Fracture characterization and porosity and permeability can be estimated using resistivity or acoustic borehole imaging tools.Also,borehole seismic data can help with fracture characterization. Fractured basement reservoir connectivity can be confirmed using wireline formation testing and sampling(WFT)or drill stem tests(DSTs).In addition,because not all open fractures produce,it is important to identify the critically stressed fractures that will contribute to production using geomechani- cal analysis.Comparing results from the study area with other fractured basement matrices and fracture porosity and permeability ranges was helpful in validating the analysis and predicting reservoir perfor- mance. This paper presents a proposed workflow for a set of data acquisition and characterization technologies and methods using a local example from an offshore Malay basin.The pros and cons of each technology and methodology proposed are discussed in detail.