CSEM monitors data from hydraulic fracturing in drills

Hydraulic fracturing plays a key role in increasing the reserves and production of unconventional oil and gas resources. Injecting fracturing fluid into the ground to improve reservoirs also introduces the risk of inducing earthquakes, so predicting the migration of fracturing fluid is very important. The micro-seismic positioning method determines the fracture development trend by locating the micro-seismic events generated by fractured rock strata, then infers the distribution location of the fracturing fluid, but this method is susceptible to error. The wide application of electromagnetic method monitoring, along with the rapid development of equipment and the low-resistivity characteristics of fracturing fluid, provide experience, equipment and physical property basis for monitoring fracturing by electromagnetic method. In order to resist the electromagnetic noise of the drilling environment and obtain a reliable electromagnetic response, a high-power transmitter with long conductor grounding for transmitting current is used to establish an electromagnetic field, and the distance between the surface observation array and transmission source is minimized to improve the signal strength. The monitoring test data of Well Eyangye-2HF show that the time-lapse controlled-source electromagnetic (CSEM) method is suitable for hydraulic fracturing and has good monitoring effects. The CSEM results also could complement deficiencies in micro-seismic monitoring. The electric field (Ex) observed by the CSEM method can directly predict the distribution edge of the fracturing fluid, and the anomalous zone of the Ex change rateis consistent with the fracturing fluid injection data and the micro-seismic monitoring results. The 3D forward simulation results show that the time-lapse CSEM monitoring adopted in this paper is feasible for use in hydraulic fracturing monitoring.