A Petrophysical Interpretation Framework Supporting The Development Of Geological, Geophysical And Engineering Models

Interpretation demographics are continually changing. What has been the traditional province of the log analyst and petrophysicist has increasingly become a part of the activity performed by geologists, geophysicists, and engineers. In many cases, these ?new users? are unfamiliar with the response-equation-based approach for log data analysis and interpretation. This approach readily supports assessing log data quality, correcting log data for borehole effects resulting in improved synthetics, and determining the formation mineral and fluid components, along with their uncertainties. Other applications include reservoir monitoring and fluid substitution of logs in support of interpretation and calibration of 3D and 4D seismic. Gains in analyst?s productivity and expansion of the user base are best realized if the response equation-based log interpretation approach is part of the fundamental interpretation system used by the geologist, geophysicist, and engineer. The difficulties in learning this approach are offset by the need for only a single program for formation evaluation, fluid substitution, and the generation of synthetic logs. In addition, when feasible, the economics of obtaining all this information from just cased hole data are obvious. This paper presents an overview of a response-equation-based log interpretation approach. The paper highlights how log quality, uncertainty of results, and the generation of ?theoretical logs? for improved synthetics are handled by the approach. A field example illustrates that reservoir monitoring with carbon/oxygen (C/O) logs is readily handled by the response-equation-based approach. The response equations for C/O interpretation are presented. By constraining the model to utilize porosity and clay volume obtained from open hole interpretation, hydrocarbon saturation can be obtained. By generalizing the model to include the capture silicon, calcium, and hydrogen yields, it is possible to extend the model to situations where open hole porosity and mineralogy may not be available. Still another field example demonstrates that it is possible to generate synthetic or theoretical open hole logs such as density, neutron, sonic from the cased hole response-equation-based interpretation results. The theoretical open hole logs obtained with this approach are compared with results obtained using a neural network. Interpretation demographics are continually changing. What has been the traditional province of the log analyst and petrophysicist has increasingly become a part of the activity performed by geologists, geophysicists, and engineers. In many cases, these ?new users? are unfamiliar with the response-equation-based approach for log data analysis and interpretation. This approach readily supports assessing log data quality, correcting log data for borehole effects resulting in improved synthetics, and determining the formation mineral and fluid components, along with their uncertainties. Other applications include reservoir monitoring and fluid substitution of logs in support of interpretation and calibration of 3D and 4D seismic. Gains in analyst?s productivity and expansion of the user base are best realized if the response equation-based log interpretation approach is part of the fundamental interpretation system used by the geologist, geophysicist, and engineer. The difficulties in learning this approach are offset by the need for only a single program for formation evaluation, fluid substitution, and the generation of synthetic logs. In addition, when feasible, the economics of obtaining all this information from just cased hole data are obvious. This paper presents an overview of a response-equation-based log interpretation approach. The paper highlights how log quality, uncertainty of results, and the generation of ?theoretical logs? for improved synthetics are handled by the approach. A field example illustrat