A multi-perforation staged fracturing experimental study on hydraulic fracture initiation and propagation

Abstract

Hydraulic fracture initiation and propagation are extremely important on deciding the production capacity and are crucial for oil and gas exploration and development. Based on a self-designed system, multi-perforation cluster-staged fracturing in thick tight sandstone reservoir was simulated in the laboratory. Moreover, the technology of staged fracturing during casing completion was achieved by using a preformed perforated wellbore. Three hydraulic fracturing methods, including single-perforation cluster fracturing, multi-perforation cluster conventional fracturing and multi-perforation cluster staged fracturing, were applied and studied, respectively. The results clearly indicate that the hydraulic fractures resulting from single-perforation cluster fracturing are relatively simple, which is difficult to form fracture network. In contrast, multi-perforation cluster-staged fracturing has more probability to produce complex fractures including major fracture and its branched fractures, especially in heterogeneous samples. Furthermore, the propagation direction of hydraulic fractures tends to change in heterogeneous samples, which is more likely to form a multi-directional hydraulic fracture network. The fracture area is greatly increased when the perforation cluster density increases in multi-perforation cluster conventional fracturing and multi-perforation cluster-staged fracturing. Moreover, higher perforation cluster densities and larger stage numbers are beneficial to hydraulic fracture initiation. The breakdown pressure in homogeneous samples is much higher than that in heterogeneous samples during hydraulic fracturing. In addition, the time of first fracture initiation has the trend that the shorter the initiation time is, the higher the breakdown pressure is. The results of this study provide meaningful suggestions for enhancing the production mechanism of multi-perforation cluster staged fracturing.

Analytical Solution and Simulation of Oil Deliverability Analysis for Reorientation Hydraulic Fracture in Low-Permeability Reservoirs

“…The stresses surrounding the fracture decrease when a fractured well output for some time [14][15][16]. During a repeated fracturing treatment, if the directions of the maximum formation stress changes, the new fracture and original fracture could be at a certain angle [17,18]. The results of the laboratory test, as showing in Figure 1, also proved that the directions of refracture are not all along the original fracture direction [19,20].…”

Research and Application of Coal Seam Permeability Improvement Technology by Sectional Directional Hydraulic Fracturing

“…Te initial coal seam cracks that form as a result of the coal seam's opening and growth widen and connect to form a fracture network, which changes the coal seam's gas fow state from difusion to nonlinear seepage to linear seepage and improves the coal's permeability. Te desorption impact of coal adsorption gas may also be increased by an increase in cracks, allowing more adsorbed gas to be transformed into free gas and accelerating extraction while decreasing the gas amount in the coal seam and enhancing gas extraction efciency [25][26][27][28][29].…”

Experimental Study on the Initiation and Propagation of Multi-Cluster Hydraulic Fractures within One Stage in Horizontal Wells

“…The cyclic pumping method is worth investigating in the initiation and propagation of multiple fractures. Other researchers [29][30][31] have also carried out experimental studies.…”