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Collaborating Authors
Results
ABSTRACT The purpose of this petrophysical study is the refinement of previously developed log analysis methods and the determination of empirically derived net pay parameters which can be used by the log analyst in exploration, property enhancement, and acquisition studies. Twenty-one wells were selected in the study area for evaluation based on the availability of "modern" log suites, multiplicity of tests, and geographic distribution. Oil production in the study area is established from the Mississippian Ratcliffe and Mission Canyon, the Devonian Nisku, Duperow, and Winnipegosis, the Silurian Interlake, and the Ordovician Gunton and Red River carbonates. Computer-assisted log analysis was used to evaluate all significant porosity development, whether tested or untested, in these formations for the 21 wells. Net pay parameters minimum cutoffs for oil saturation and resistivity ratios, and maximum cutoffs for bulk volume water) were then established, by formation, by comparing the reported fluid recovery from drillstem and perforation tests with log analyses for the tested intervals. Minimum porosity cutoffs for total porosity and matrix porosity were accepted as 0.06 unless otherwise indicated by test results. Within the context of this study, the accuracy of log analysis is defined as a measure of the ability to determine the commercial potential of a zone of interest by the analysis of log data. A comparison of log analysis results (net pay determination) with test results (fluid recoveries) demonstrates good log analysis accuracy. Significant untested pay potential is indicated in many of the wells evaluated. Most of the untested pay potential is in the Ratcliffe, Mission Canyon, Nisku, Duperow, Winnipegosis, and Interlake formations. The application of these log analysis methods and net pay parameters should improve success rates for those projects in which log analysis is critical.
- North America > United States > South Dakota > Williston Basin (0.99)
- North America > United States > Montana > Williston Basin (0.99)
- North America > United States > North Dakota > Williston Basin > Red River Formation (0.98)
The evaluation of shaly sand formations can be made using any paired combination of density log, neutron log, and acoustic log. Assuming only water is present in the formation, the logs" responses are defined by the following equations: where p = density $ = effective porosity & = neutron porosity At = transit time measurement from the acoustic log Subscripts refer to b = bulk or total formation ma = matrix sh = shale f = fluid in the pore space Given two different logs, their equations may be solved simultaneously for the effective porosity and shale per cent. However, this method is tedious when hand calculating a shale/sand sequence; an alternative approach of cross-plotting the data and graphically solving the equations is usually followed. The cross-plot technique has the disadvantage of at times also being tedious and insufficiently precise. Therefore, an analytical technique resulting in an easily used equation for porosity and shale per cent is desirable. These equations are obtained by mathematically describing the shaly-sand crossplot. The derivation of the porosity and shale per cent equations is presented in the following section assuming 100% water saturated sand. The following two sections present the derivation for a gas or light hydrocarbon correction in clean sands and in shaly sands. The density-neutron log combination is of primary concern in this paper and only this cross-plot will be discussed. However, the same derivation technique and calculation procedures discussed here are applicable to the other log combinations.
- North America > United States > Oklahoma (1.00)
- North America > United States > Ohio (1.00)
- North America > United States > Louisiana (1.00)
- (8 more...)
- Government > Regional Government > North America Government > United States Government (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- South America > Argentina > Jujuy > Salta Basin > Caimancito Field (0.99)
- South America > Argentina > Jujuy > Noroeste Basin > Caimancito Field (0.99)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Deep Basin > Pembina Field > Viking Formation (0.99)
- (5 more...)