Experimental Study on Injection Pressure Response and Fracture Geometry during Temporary Plugging and Diverting Fracturing

Abstract

Summary Temporary plugging and diverting fracturing (TPDF) has become one of the fastest-growing techniques to maximize the stimulated reservoir volume (SRV). During the field operation of TPDF, diverters are injected to redirect the hydraulic fractures into the under-stimulated region of the reservoir, and, thus, to obtain better coverage of the created fracture network. In this study, the commonly used true tri-axial hydraulic fracturing system is modified to investigate the influences of various factors on the injection pressure response and resultant fracture geometry during diversion treatments. The experimental results show the feasibility of creating multiple fractures through TPDF, and more importantly give the following findings: (1) a complex diverted fracture network tends to be created at a small differential stress (2.5 MPa in this case), while diverted fractures tend to grow parallel to the initial fractures at a high differential stress (7.5 MPa in this case); (2) with the same concentration in the fracturing fluid, 40-mesh powder-shaped diverters can plug the created fractures and increase the net pressure more rapidly than 6-mm fiber-shaped diverters; (3) an excess of diverters can lead to a strong injection pressure response, and, thus, enhance the difficulty of creating multiple fractures; (4) when diverters are injected with the fracturing fluid, no obvious breakdown pressure or propagation pressure is shown during the fracture propagation.

Experimental Study on the Transport Law of Different Fracturing Granular Materials in Fracture

“…Plugging the major fracture by injecting a temporary plugging agent (TPA) to force the fracturing fluid to turn and open the natural fractures is an important method to form complex fracture networks. − In addition, for the old wells with declining production, TPA also is used to block the initial fractures and form new fractures in other directions . At present, most of the temporary plugging fracturing experiments are carried out in rock, and the results show that the TPA can plug the major fracture to increase the fracture complexity . Granular TPA has been widely used because of its advantages such as safe construction, easy regulation of particle size, and convenient operation and transportation .…”

Hydrofracture plugging mechanisms and evaluation methods during temporary plugging and diverting fracturing

“…evaluation of temporary plugging, extended finite element method, reservoir stimulation, unconventional oil/gas 1…”

“…As shown in Figure 1, TPDF can be divided into four categories according to the construction purpose: (1) inplane TPDF near the wellbore, staged TPDF along the horizontal well, layered TPDF along the vertical well, and in-fracture TPDF. 1 Similarly, diverters are injected to plug the previously created hydrofractures, and the net pressure can be enhanced to a high level within the wellbore or the hydrofractures; the subsequent fluids can then be diverted to the unstimulated layer, perforation clusters, and thus, the stimulated volume of the reservoir can be enlarged greatly. After that, the diverter can be dissolved within the fracturing fluids, flow back to the ground, and do no damage to the reservoir.…”

Modeling Temporary Plugging Agent Transport in the Wellbore and Fracture with a Coupled Computational Fluid Dynamics–Discrete Element Method Approach

“…During a fracturing process, a water-soluble temporary plugging agent is added to the fracturing fluid once or several times. The temporary plugging agents seal the initial fractures, forcing the fluid to divert and promote the opening and extension of new fractures. − There is a long history for using solid diverting agents for enhancing stimulation treatments. The earliest patent of a diverting agent was in 1936, issued to Clason .…”