Method of ultra long spaced electric logging of a well bore to detect horizontally disposed geologically anomalous bodies in the vicinity of massive vertically disposed geologically anomalous bodies lateral to and not intercepted by the well bore

Claim 1

A method of determining the presence and fixing the location of a horizontally disposed, electrically resistive geological anomaly in an earth formation lateral to but not cut by a well bore when said anomaly lies in the vicinity of a massive vertically disposed, electrically resistive geological anomaly likewise lateral to but not cut by said well bore, comprising: a. traversing said well bore with an electrode array comprising a current source electrode, A, to pass current into earth formations cut by said well bore, a first potential electrode, M, positioned a first predetermined vertical distance below said source electrode, and a second potential electrode, N, positioned a second predetermined vertical distance above said source electrode, said electrodes forming a ''''split array'''' spanning a given interval of said well bore, b. energizing said current source electrode, A, and a sink electrode, B, at the earth''s surface to pass current into said formations cut by said well bore as well as formations lateral to but not cut by said well bore and measuring the difference of potential between said first and said second potential electrodes, M and N, c. determining the apparent resistivity Rho A over the spanned interval between said potential electrodes including said earth formations cut by and lateral to but not cut by said well bore in accordance with the relationship: Rho A (4 pi Delta V/IG) where Delta V measured potential difference between potential electrodes, M and N I current emitted by source electrodes G tool geometry factor 1/AM - 1/AN where AM distance from the current source electrode A to potential electrode A beneath it, taken negative, AN distance from the current source electrode A to potential electrode N above it, taken positive, d. comparing said apparent resistivity, determined in accordance with said relationship with resistivity data collected by other electric logging means than said ''''split array'''' configuration of step (a) over said spanned interval, the differences between said apparent resistivity and the comPared resistivity data indicating the presence and magnitude of horizontally disposed, electrically resistive geological anomalies lateral to and not cut by said well bore and in the presence of said vertically disposed, electrically resistive geological anomalies.

Claim 2

A method of determining the presence and fixing the location of a horizontally disposed, electrically resistive geological anomaly in an earth formation lateral to but not cut by a well bore when said anomaly lies in the vicinity of a massive vertically disposed, electrically resistive geological anomaly likewise lateral to but not cut by said well bore, comprising: a. traversing said well bore with an electrode array comprising a current source electrode, A, to pass current into earth formations cut by said well bore, a first potential electrode, M, positioned a first predetermined vertical distance below said source electrode, and a second potential electrode, N, positioned a second predetermined vertical distance above said source electrode, said electrodes forming a ''''split array'''' spanning a given interval of said well bore, b. energizing said current source electrode, A, and a sink electrode, B, at the earth''s surface to pass current into said formations cut by said well bore as well as formations lateral to but not cut by said well bore and measuring the difference of potential between said first and said second potential electrodes, M and N, c. determining the apparent resistivity Rho A over the spanned interval between said potential electrodes including said earth formations cut by and lateral to but not cut by said well bore in accordance with the relationship: Rho A (4 pi Delta V/IG) where Delta V measured potential difference between potential electrodes, M and N I current emitted by source electrodes G tool geometry factor 1/AM - 1/AN where AM distance from the current source electrode A to potential electrode A beneath it, taken negative, AN distance from the current source electrode A to potential electrode N above it, taken positive, d. comparing said apparent resistivity, determined in accordance with said relationship with resistivity data collected by other electric logging means than said ''''split array'''' configuration of step (a) over said spanned interval, the differences between said apparent resistivity and the comPared resistivity data indicating the presence and magnitude of horizontally disposed, electrically resistive geological anomalies lateral to and not cut by said well bore and in the presence of said vertically disposed, electrically resistive geological anomalies.

Claim 9

A method of determining the presence and fixing the location of a horizontally disposed, electrically resistiv geological anomaly in an earth formation lateral to but not cut by a well bore when said anomaly lies in the vicinity of a massive vertically disposed, electrically resistive geological anomaly lateral to but not cut by said well bore, comprising: a. traversing said well bore with an electrode array comprising a current source electrode, A, to pass current into earth formations cut by said well bore, a first potential electrode, M, positioned a predetermined vertical distance greater than 75 feet below said source electrode, and a second potential electrode, N, positioned said predetermined vertical distance greater than 75 feet above said source electrode, said electrodes forming a ''''split array'''' spanning a given interval of said well bore, b. energizing said current source electrode, A, and a sink electrode, B, at the earth''s surface, to pass current into said formations cut by said well bore as well as formations lateral to but not cut by said well bore and measuring the difference of potential between said first and said second potential electrodes, M and N, c. determining the apparent resistivity of the spanned interval between said potential electrodes including said earth formations cut by and lateral to but not cut by said well bore in accordance with the relationship: Rho a (4 pi Delta V/IG) where Delta V measured potential difference between potential electrodes, M and N I current emitted by source electrodes G tool geometry factor 1/AM - 1/AN where AM distance from the current source electrode A to potential electrode M, taken negative AN distance from the current source electrode A to potential electrode N, taken positive d. comparing said apparent resistivity, determined in accordance with said relationship with resistivity data collected by other electric logging means than said ''''split array'''' configuration of step (a) over said spanned interval, the differences between said apparent resistivity and the compared resisitivity data indicating the presence and magnitude of horizontally disposed, electrically resistive geological anomalies lateral to and not cut by said well bore and in the presence of said vertically disposed, eLectrically resistive geological anomalies.

Claim 10

A method of determining the presence and fixing the location of a horizontally disposed, electrically resistiv geological anomaly in an earth formation lateral to but not cut by a well bore when said anomaly lies in the vicinity of a massive vertically disposed, electrically resistive geological anomaly lateral to but not cut by said well bore, comprising: a. traversing said well bore with an electrode array comprising a current source electrode, A, to pass current into earth formations cut by said well bore, a first potential electrode, M, positioned a predetermined vertical distance greater than 75 feet below said source electrode, and a second potential electrode, N, positioned said predetermined vertical distance greater than 75 feet above said source electrode, said electrodes forming a ''''split array'''' spanning a given interval of said well bore, b. energizing said current source electrode, A, and a sink electrode, B, at the earth''s surface, to pass current into said formations cut by said well bore as well as formations lateral to but not cut by said well bore and measuring the difference of potential between said first and said second potential electrodes, M and N, c. determining the apparent resistivity of the spanned interval between said potential electrodes including said earth formations cut by and lateral to but not cut by said well bore in accordance with the relationship: Rho a (4 pi Delta V/IG) where Delta V measured potential difference between potential electrodes, M and N I current emitted by source electrodes G tool geometry factor 1/AM - 1/AN where AM distance from the current source electrode A to potential electrode M, taken negative AN distance from the current source electrode A to potential electrode N, taken positive d. comparing said apparent resistivity, determined in accordance with said relationship with resistivity data collected by other electric logging means than said ''''split array'''' configuration of step (a) over said spanned interval, the differences between said apparent resistivity and the compared resisitivity data indicating the presence and magnitude of horizontally disposed, electrically resistive geological anomalies lateral to and not cut by said well bore and in the presence of said vertically disposed, eLectrically resistive geological anomalies.