Method for measuring electrical resistivity of earth layer around oil well through sleeve pipe

Abstract

The invention provides a method for measuring the electrical resistivity of the earth layer around an oil well through a sleeve pipe, which comprises the following steps: providing an upper current electrode and a lower current electrode for respectively exerting current on the sleeve pipe and the earth layer; providing at least three measuring electrodes and using the earth layer resistivity corresponding to the middle measuring electrode as the final measuring target; measuring the intensity of the current provided by the upper electrode and the lower electrode, the potential of the middle measuring electrode and the potential difference between each measuring electrode; respectively setting a point A and a point B as the contact points of the upper current electrode, the lower current electrode and the sleeve pipe; respectively setting M1, N and M2 as the contact points of three measuring electrodes and the sleeve pipe; and making the calculation through certain formulas to obtain the apparent resistivity. The invention is favorable for eliminating the influence of the electric resistance change of the sleeve pipe on the final measuring results.

Description

technical field [0001] The invention relates to a method for measuring the resistivity of the formation around the oil well, in particular to a method for measuring the resistivity of the formation around the oil well through a casing. Background technique [0002] Measuring the resistivity of the formation is an important method to find out the oil reserve of the oil layer and the distribution of the oil layer. In the open hole without casing, the resistivity of the formation can be determined by injecting current into the formation, measuring the potential of the corresponding formation and using the corresponding calculation method, but in the oil well with casing, due to the influence of the casing on the current However, in many old wells, due to the passage of time and the difference in technology in previous open-hole well measurements, many oil layers have not been discovered, and oil and gas resources are becoming increasingly depleted. Today, it is necessary to re...

AI Technical Summary

Problems solved by technology

In the open hole without casing, the resistivity of the formation can be determined by injecting current into the formation, measuring the potential of the corresponding formation and using the corresponding calculation method, but in the oil well with casing, due to the influence of the casing on the current However, in many old wells, due to the passage of time and the difference in technology in previous open-hole well measurements, many oil layers have not been discovered, and oil and gas resources are becoming increasingly depleted. Today, it is necessary to re-measure the cased hole to realize its potential

[0003] The prior art method similar to this method is to apply current to the cased well, and determine the resistivity of the casing with multiple measuring electrodes and multi-step measurements to obtain the resistivity of the formation. This technique requires that the measuring electrodes be placed symmetrically, And when the casing resistance changes, the measured value of the formation around the oil well will be greatly distorted, and a certain correction method is required to correct this situation, and there are other similar technical methods that have large differences in the measurement method. the difference

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