Investigate The Rheological Behavior of High Viscosity Friction Reducer Fracture Fluid and Its Impact on Proppant Static Settling Velocity

Abstract

The recent and rapid success of using high viscosity friction reducers (HVFRs) in hydraulic fracturing treatments is due to several advantages over other fracture fluids (e.g. linear gel), which include better proppant carrying capability, induce more complex fracture system network with higher fracture length, and overall lower costs due to fewer chemicals and less equipment on location. However, some concerns remain, like how HVFRs rheological properties can have impact on proppant transport into fractures. The objective of this study is to provide a comprehensive understanding of the influence the rheological characterization of HVFRs have on proppant static settling velocity within hydraulic fracturing process. To address these concerns, comprehensive rheological tests including viscosity profile, elasticity profile, and thermal stability were conducted for both HVFR and linear gel. In the steady shear-viscosity measurement, viscosity behavior versus a wide range of shear rates was studied. Moreover, the influence of elasticity was examined by performing oscillatory-shear tests over the range of frequencies. Normal stress was the other elasticity factor examined to evaluate elastic properties. Also, the Weissenberg number was calculated to determine the elastic to viscous forces. Lastly, quantitative and qualitative measurements were carried out to study proppant settling velocity in the fluids made from HVFRs and linear gel. The results of rheological measurement reveal that a lower concentration of HVFR-2 loading at 2gpt has approximately more than 8 times the viscosity of linear gel loading at 20ppt. Elastic measurement exposes that generally HVFRs have a much higher relaxation time compared to linear gel. Interestingly, the normal stress N1 of HVFR-2, 2gpt was over 3 times that of linear gel loading 20ppt. This could conclude that linear gel fracture fluids have weak elastic characterization compared to HVFR. The results also concluded that at 80 C° linear gel has a weak thermal stability while HVFR-2 loses its properties only slightly with increasing temperature. HVFR-2 showed better proppant settling velocity relative to guar-based fluids. The reduction on proppant settling velocity exceed 75% when HVFR-2 loading at 2gpt was used compared to 20ppt of linear gel. Even though much work was performed to understand the proppant settling velocity, not much experimental work has investigated the HVFR behavior on the static proppant settling velocity measurements. This paper will provide a better understanding of the distinct changes of the mechanical characterization on the HVFRs which could be used as guidance for fracture engineers to design and select better high viscous friction reducers.

Preparation and Performance Evaluation of a Variable Viscosity Friction Reducer Suspension with High Salt Tolerance and Low Damage

“…Here, a parameter “relaxation time” was introduced to analyze the elasticity of the EACM solution, which is defined as the reciprocal of the angular frequency corresponding to the intersection point of elastic modulus and viscous modulus in Figure B. The larger the relaxation time, the better the elasticity and proppant-carrying capacity of the solution . When the EACM concentration was higher than 0.21 wt %, the relaxation time increased with the increase in EACM concentration, so the proppant-carrying capacity enhanced.…”

“…The larger the relaxation time, the better the elasticity and proppantcarrying capacity of the solution. 53 When the EACM concentration was higher than 0.21 wt %, the relaxation time increased with the increase in EACM concentration, so the proppant-carrying capacity enhanced. When the EACM concentration was lower than 0.21 wt %, the elastic modulus was always less than the viscous modulus, implying that the EACM solution with EACM concentration below and above 0.21 wt % exhibited viscous and elastic characteristics over the frequency range, respectively.…”

Performance Evaluation of the Multifunctional Variable-Viscosity Slick Water for Fracturing in Unconventional Reservoirs

“…Two major features of slick water are sand-carrying and drag-reducing properties, but most conventional slick water is not effective at carrying sand. It is therefore important to research the performance difference between high-viscosity slick water and multifunctional variable-viscosity slick water in carrying sand and drag reducing. − …”

Microfluidic Rheometry and Particle Settling: Characterizing the Effect of Polymer Solution Elasticity

“…For polymer-based frac fluids, considering the importance of polymer type, structure, solubility and charge, the most common variables to alter when formulating new solutions are the polymer molecular weight, M w , and the polymer concentration, c. Equation (4) at Re << 1 and zero elasticity, Wi = 0 reduces to the base visco-inelastic (or Newtonian) C D = 24 /Re (Kelbaliyev, 2011). At higher elasticity, drag coefficient on the particle may increase or decrease depending of flow conditions Fundamentally, the relative settling velocity of a single particle is measured as the first order of accuracy to evaluate the proppant carrying capacity of a hydraulic fracturing fluid (Elgaddafi et al, 2016, Geri et al, 2019, Geri and Imqam, 2019. To better evaluate the proppant carrying capacity of a fluid, a full consideration of several interacting factors, including but not limited to (i) particle-fluid interactions (4-way coupling), (ii) particle-fracture interactions, and (iii) reservoir physiochemical and geomechanical behaviors, should be taken into account.…”

“…Dilute polymeric solutions, in this work, refer to a solution with 0.01 ≤ c /c * ≤ 1, where c * is the overlap concentration [22,24]. Despite the complexity of such systems, the particle-carrying capacity of a fluid is estimated by mapping the translation of a single sphere in inertia-less steady-state conditions [25,26]. In hydraulic fracturing, the importance of this measuring criterion has been originated by the low shear rate conditions experienced by particles within the fractures after the pressure release.…”