The Monitor of Fracture Azimuth Based on Pseudo Random Emission Current

Fracturing is an important segment in the sequences of exploring oil, which is also the indispensable means of increasing gas production. Resistivity difference is the premise of monitoring fracture azimuth. We can inject high ionization working liquid into fracturing layer, which lead to the changes of formation resistivity. But because the oil is deep, so the changes of surface potential gradient is small. At the same time, there are all kinds of natural and artificial noise on the earth. So our measuring instrument must have strong anti-interference ability and high accuracy. It can restrain noise by adopting the pseudo random signal as artificial field source and use correlation detection principle. So we can extract the surface potential gradient caused by artificial field source and improve the accuracy of judging fracture extension direction.