Effect of the Type of Fracturing Fluid on the Breakdown Pressure of Tight Sandstone Rocks

Abstract

Hydraulic fracturing is performed to enhance production in reservoirs with low permeability. It's an effective technique but there are still several uncertainties associated in its implementation. One of the uncertainties is the dependence of breakdown pressure on the type of fracturing fluid used. The objective of this paper is to perform an experimental study to determine the role of fracturing fluid on the breakdown pressure of tight sandstone rocks. The dimensions of the samples are 2 in. (diameter) by 2 in. (length). A hole of 0.25-in. in diameter and 0.75-in. length is drilled on one face of each core through which the fracturing fluid is pumped. A strong power relation between the viscosity of the fracturing fluid and breakdown pressure was seen. As the viscosity increased, the breakdown pressure increased significantly. Computed Tomography (CT) scan showed that the direction of fracture is along the bedding plane. As the viscosity increased, the fracture width and height increased. For most tests, the fractures created were bi-wing fractures. Some single wing fractures were created due to deformities in the borehole.

Role of Rock Saturation Condition on Rock–Mud Interaction: Sandstone Geomechanics Study

“…The result showed that the sonic wave velocities for the dry and brine-saturated rock samples generally increased after the mud exposure as the compressional wave velocities (Vp) increased by 3 and 9% for the dry and brine-saturated samples, respectively, while the shear wave velocities (Vs) showed a slight increase of around 1%. On the other hand, the oil-saturated sample showed a reduction in the sonic wave velocities after mud exposure as Vp and Vs decreased by 17 and 16.5%, respectively, and this observation was ascribed to the mud filtrate replacement for the oil fluid from the rock pores; and the high oil viscosity affected the wave velocities as the oil-saturated sample has high velocities due to the fast propagation for the sonic waves …”

“…The rock strength reduction is a common conclusion that can be observed for the rock water-saturation phase; in addition, the propagation of the acoustic wave is affected by the saturation condition and showed increased performance, and the rock porosity controls the degree of saturation impact on the rock physical–mechanical characteristics . The interior pore system is very critical for propagating the acoustic waves, and studies through the literature reported that rock mineralogy significantly affects the shear wave, while the saturating fluid greatly affects the compressional wave type through the sonic data acquisition. ,, The effect of fluid saturation on rock geomechanics was studied for tight sandstone formation, and it was found that the strength reduction was higher for the brine-saturated samples than for the rock samples with oil saturation …”

“… 20 , 53 , 54 The effect of fluid saturation on rock geomechanics was studied for tight sandstone formation, and it was found that the strength reduction was higher for the brine-saturated samples than for the rock samples with oil saturation. 55 …”

Numerical study of the influence of seepage force on the stress field around a vertical wellbore

“…These three stress fields are in-situ stress, wellbore pressure and poroelastic stress caused by pore pressure variations at various points after the fluid flows into the pore (Haimson, 1968;Haimson & Fairhurst, 1967, 1969a, 1969bHubbert & Willis, 1972). Subsequently, many scholars (Aadnoy & Belayneh, 2009;Chatterjee & Mukhopadhyay, 2003;Ito & Hayashi, 1991;Ito, 2008;Kiss et al, 2018;Medlin & Masse, 1979;Muqtadir et al, 2018;Rummel, 1987;Song et al, 2017;Wang et al, 2018) have contributed their efforts to study the fracture initiation mechanism of hydraulic fracturing and wellbore stability based on Haimson and Hubbert's theoretical models. By comparing laboratory experiments with theoretical predictions, Medlin and Masse (1979) proposed that the theoretical prediction results could only be partially verified when the fracturing fluid is permeable.…”

“…Based on the traditional calculation theory, Song et al (2017) analyzed the effect of nanoparticle drilling fluid on the wellbore stability of shale reservoirs using the twodimensional fluid-solid coupling module in FLAC3D software. Muqtadir et al (2018) investigated the effect of the type of fracturing fluid on the fracture pressure of tight sandstone rocks. Do et al (2019) investigated the stability of wellbores drilled in anisotropic permeable rocks, taking into account the transient effect of fluid flow.…”