Modeling reference fracture pressures to design hydraulic fracture operations using well logging data

摘要

Hydraulic fracturing is one of the common methods to increase the efficiency and production of oil and gas reservoirs. Low-permeable rocks are good candidates for creating a hydraulic fracture since the fracture creates a permeable path that connects the reservoir and the well. To perform hydraulic fracture operations, it is necessary to conduct geomechanical studies, with their most important outputs being formation fracture pressure and direction of fracture. As the most important input data in this study, well logging was used to build a mechanical model of the earth for the rock and then estimate the fracture pressure, accordingly. In the studied well, the tensile fracture pressure in this rock is in the range of 17.87 ppg-23.74 ppg in all directions. In this case, by increasing the angle of the well, the pressure required for tensile fracture is increased such that the fracture pressure of the well wall was 23.74 ppg and 17.87 ppg, respectively, in horizontal and vertical wells. The studied well was vertical in which the pressure required to create a hydraulic fracture was about 17.9 ppg. Also, in this well, the angle of fracture was 135 in the direction of Azimuth. Meanwhile, with increasing the angle of the well and becoming more horizontal, the tendency of the well to break in the 45-degree azimuth direction (i.e., the maximum horizontal stress) is increased. Factors such as azimuth, minimum horizontal stress, Biot number, maximum horizontal stress, formation pressure, and Poisson's ratio can also have a significant effect on fracture pressure to create a fracture.