Experimental Evaluation of Guar Fracture Fluid Filter Cake Behavior

Abstract

Guar gum and its derivatives have been the most commonly used polymers to increase the viscosity of fracturing fluids. However, the conductivity of many fractures created with guar-based polymers is low because of residual unbroken polymer gel remaining in the fracture. This residue can cause permeability impairment in the proppant pack resulting in low fracture conductivity and decreased effective fracture length. In this study, we experimentally evaluated two important aspects of the gel damage process - the thickness of the polymer gel filter cake that is created as fracture fluid filtrate leaks off into the formation, and the yield stress of the concentrated polymer gel that accumulates in the fracture. The thickness of the filter cake created during the leakoff process was measured as a function of the polymer loading and the volume of leakoff. We created the filter cake following the procedure described by Ayoub et al. (2006), then measured the filter cake thickness with a precise laserprofilometer. We found that the filter cake thickness varied linearly with leakoff volume, meaning that the gel concentration factor is constant for this guar polymer fluid. The concentrated polymer filter cakes created by leakoff behave rheologically as Herschel-Bulkley fluids having a yield stress. The yield stress of this material is a critical parameter influencing whether or not the gel can be removed from the fracture. We measured the yield stress of borate-crosslinked guar polymer fracture fluids at concentrations up to 200 lb/mgals using a unique flat plate device. The yield stresses of th polymer filter cakes were found to depend strongly on the concentration of both polymer and breaker.

Formation Damage due to Drilling and Fracturing Fluids and Its Solution for Tight Naturally Fractured Sandstone Reservoirs

“…Gel is typically used as the fracturing fluid to maximize the proppant-carrying capacity because of its excellent viscosity and elasticity [17][18][19][20][21][22]. However, gel residuals can block fractures and pores at fracture faces, thus impeding the flow of hydrocarbon [23][24][25]. Besides gel residuals, water can imbibe rock matrix and cause phase trapping, which reduces hydrocarbon permeability due to multiphase flow [26][27][28][29].…”

Study of Nanoparticle–Surfactant-Stabilized Foam as a Fracturing Fluid

“…However, guar gum forms an insoluble residue in the formation, and these insoluble materials plug pore throats, causing impaired leakoff and formation damage that could be fatal to tight and shale gas reservoirs. 6,7 Moreover, the price of guar gum fluctuates a lot depending on the market, costing more to companies worldwide. 8,9 Foam fracturing fluids are attracting much attention because the liquid content of a foam fluid is very small, thus reducing the damage potential to sensitive formations.…”

Preparation of a nanosilica cross‐linker and investigation of its effect on properties of guar gum fracturing fluid

“…and NPs: Traditional fracturing fluids use viscosifying agents (such as Guar gum and its derivatives) to support and carry the proppant. However, guar gum forms insoluble residue which plugs pore throats and causes impaired leak-off, thereby causing fatal damage to tight and shale gas reservoirs [22,23]. Table 1 shows the breaking performance of the guar gum gels cross-linked by borate and NPs.…”