Comparison of Permeability Predictors from NMR, Formation Image and Other Logs in a Carbonate Reservoir

Abstract

Comparison of Permeability Predictors from NMR, Formation Image and other Logs in a Carbonate Reservoir J. K. Hassall; J. K. Hassall Abu Dhabi Company for Onshore Oil Operations Search for other works by this author on: This Site Google Scholar P. Ferraris; P. Ferraris Schlumberger Search for other works by this author on: This Site Google Scholar M. Al-Raisi; M. Al-Raisi Schlumberger Search for other works by this author on: This Site Google Scholar N. F. Hurley; N. F. Hurley Colorado School of Mines Search for other works by this author on: This Site Google Scholar A. Boyd; A. Boyd Schlumberger-Doll Research Search for other works by this author on: This Site Google Scholar D. F. Allen D. F. Allen Schlumberger-Doll Research Search for other works by this author on: This Site Google Scholar Paper presented at the Abu Dhabi International Conference and Exhibition, Abu Dhabi, United Arab Emirates, October 2004. Paper Number: SPE-88683-MS https://doi.org/10.2118/88683-MS Published: October 10 2004 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Hassall, J. K., Ferraris, P., Al-Raisi, M., Hurley, N. F., Boyd, A., and D. F. Allen. "Comparison of Permeability Predictors from NMR, Formation Image and other Logs in a Carbonate Reservoir." Paper presented at the Abu Dhabi International Conference and Exhibition, Abu Dhabi, United Arab Emirates, October 2004. doi: https://doi.org/10.2118/88683-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)Abu Dhabi International Petroleum Exhibition and Conference Search Advanced Search Abstract An extensive petrophysical analysis has been carried out on a study well in a giant carbonate field in the Lower Cretaceous of Abu Dhabi. The well was cored, and a comprehensive log suite recorded including: Nuclear Magnetic Resonance (NMR), Borehole Imaging, Shear Sonic and Mineral Spectroscopy in addition to the more normal logs.A high-resolution permeability profile was measured on the core. Plugs taken every foot were supplemented by minipermeameter measurements every inch. While this profile captures high frequency variability it is limited in its applicability to predicting reservoir behavior. Analysis of large scale flow unit permeability is better assessed with dynamic data.A number of advanced log based permeability estimators were developed in an attempt to match the core permeability profile. The estimators are based on NMR, image analysis and Stoneley measurements among others. This paper presents a comparison of these predictors to the core and makes recommendations as to the preferred permeability prediction methods for this field.For this well the Stoneley permeability correctly predicted a trend decrease of permeability with depth but failed to honor the full extent of the trend. As expected, given its vertical resolution, it also failed to respond adequately in the more heterogeneous intervals.A method based on a mean NMR T2 measurement gave a good general match to the data, but again lacked vertical resolution. An electrical image based method brings an important improvement in sensitivity to the small-scale variations in permeability, but in some places failed to follow the lower frequency trends.A composite method using the NMR to supply the overall trend, and the image to provide the higher resolution, gave the best match to the core permeability profile available from the tool suite, which was run. The method is a modification of the well-established SDR permeability equation. A new term is introduced to account for the contribution of connected vugs, which are responsible for the high permeability intervals in this well.The logs used in the methods described here do not make direct measurements of permeability. Instead permeability is inferred indirectly from measurements sensitive to parameters such as texture and pore size. It is doubtful that a single methodology based on such measurements can provide a "universal" permeability estimator fitting all cases. The methods presented here should be applied with care and will benefit greatly from calibration to spot permeability data.The method has particular application in high cost environments where a good permeability is required along the wellbore but the cost and rig time required for continuous whole coring cannot be justified. Keywords: nmr average decay time, resolution, fluid dynamics, carbonate, reservoir, well logging, core permeability, flow in porous media, perm eability, permeability Subjects: Reservoir Fluid Dynamics, Formation Evaluation & Management, Flow in porous media, Open hole/cased hole log analysis Copyright 2004, Society of Petroleum Engineers You can access this article if you purchase or spend a download.