Integration of NMR, Wireline Tester, Core and Open Hole Log Data for Dynamic Reservoir Properties

Abstract

Abstract This paper describes an integrated approach for key well evaluation using open hole well logging technology and core analysis. The information set includes nuclear magnetic resonance (NMR), wellbore electrical image, wireline formation tester, dipole sonic, conventional nuclear and resistivity logs and core data from a carbonate field. The objective was to characterize formation static and dynamic properties prior to water injection. The integrated analysis gave a good overall picture of the formation, including permeability anisotropy. Several sources of information were compared and their results were discussed. Permeability values obtained from the analysis of wireline vertical interference tests were input into the full field simulation model. Introduction An integrated data gathering and analysis approach was selected for a key well study drilled in an onshore carbonate oil field. Conventional open hole logs were used for porosity and saturation analysis while formation electrical images were used to investigate fine layering, different porosity types and fracture development within the study interval. NMR is now routinely used in sandstone formations to provide a continuous permeability log close to the borehole wall, but has not proven to be reliable in many carbonate formations. The major obstacle for using NMR to evaluate permeability in carbonates has been attributed to weak surface relaxivity, which compromises the relation between T2 and pore size distributions.1,2.Stoneley mobility indicator from dipole sonic is often used as a qualitative indicator of permeability but is difficult to scale as a quantitative measurement. Stoneley mobility indicator and wireline tester pretest mobility can compliment the NMR interpretation and improve its accuracy to provide a better continuous permeability log. The wireline formation tester was also used to conduct local vertical interference tests across tight zones to obtain in-situ vertical and horizontal permeabilities. These tests are relatively long and investigate a much larger volume of rock when compared with other open hole logs. The tests were conducted by producing from a wellbore section isolated between two inflatable packers and observing the resulting pressure response with a probe set above the tight zone. The acquired flow and pressure data was analyzed using a layered model for individual layer horizontal and vertical permeabilities. The results from this analysis were compared to core and NMR permeability data.