METHOD OF FORECAST OF EFFECTIVE CAPACITY OF COLLECTORS ON BASIS OF RECEIVED POLARIZATION PARAMETERS AND CONDUCTIVITY FOR SELECTED TYPE OF ENVIRONMENT Russian patent published in 2017 - IPC G01V3/08 

FIELD: measuring equipment.

SUBSTANCE: within the oil and gas bearing area, the differential-normalized electrical measurements (DNEM), based on the optimal network of profiles, the lateral position of the anomaly of the induced polarization associated with the hydrocarbon reservoir is determined. In the oil and gas bearing area, wells which have been studied by the data of geophysical well logging (GWL) and gas analysis (GA) are selected. The parameters of effective capacity in the studied wells on the basis of GWL data and core analysis are determined, taking them as reference ones. On sections in the form of circles around the mentioned studied wells, measurements are made or previous measurements are used by the DNEM method profiles. Then, for each section, the average value of the polarizability coefficient is determined, taking it as the reference one. The binding law is determined, which reflects the dependence of the polarizability coefficient from the effective capacity. At least three productive wells are selected in which there are data on the following parameters: total effective power, porosity coefficient, oil and gas saturation coefficient, hydrocarbon production rates, and gas analysis data. At least one unproductive well is selected according to available GWL, gas analysis and well test data. The values of effective capacity are calculated for each selected productive well. At each well, the averaged values of the polarizability and conductivity are calculated, a sample of the averaged values of the polarizability and conductivity coefficients is calculated with the subsequent calculation of the total conductivity of the drill core. For a well in which GWL data are available, the presence of correlation is verified by the correlation coefficients of the change in the values of the polarizability coefficient from the change in the effective capacity values. The conclusion about the form of the dependence of the induced polarization response from the effective capacity is made. If the correlation coefficient is not less than 0.7, then a conclusion is made about the direct dependence of the induced polarization response on the effective capacity of rocks obtained during the inversion and about the possibility of using this parameter for regression analysis. If the correlation coefficient is less than 0.7, then another polarization parameter is searched for the layer in the drill core having a correlation coefficient with effective rock capacity of at least 0.7. A complex polarizability parameter with the largest correlation coefficient between the complex polarizability parameter and the effective well capacity is selected. Regression analysis is carried out for the selected parameter in order to find the regression formula for this parameter and effective well capacity. Based on the obtained regression formula, the effective capacity is calculated on the basis of the values of the selected complex polarizability parameter within the wells. A conclusion is made about the reliability of the obtained calculated effective capacity, namely: if the values of the calculated effective capacity and effective capacity obtained from GWL data differ by an average of less than 15% and their distribution at a qualitative level is similar, this confirms the correctness of the conducted analysis. For the subsequent forecast of the effective capacity parameter, maps of smoothed values of the polarizability coefficient on the values in the target and adjacent layers are constructed at each chainage within an area of the investigation within identified polarization anomalies, and also maps of smoothed values of the total conductivity. The smoothed value at each profile chainage is obtained by averaging the values at nearby chainages. According to the obtained formula, on the basis of the values of the selected complex polarizability parameter, the effective capacity is calculated for each investigated area at each chainage of the profile.

EFFECT: improving the accuracy and efficiency of the forecast.

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