Maximizing Well Production with Unique Low Molecular Weight Frac Fluid

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractEffective fracture length is the portion of the propped fracture that cleans up after hydraulic fracturing procedure and contributes to well productivity. Studies indicate that this effective length is often less than 10% of the total propped fracture length. A large portion of our fracture stimulation dollars are wasted! This paper presents a comparative well study performed in the Cement field in south central Oklahoma. Stimulation of the Springer Sands using hydraulic fracturing with conventional low polymer fluids was compared with the use of low molecular weight polymer fracturing fluid. The depth of the three Springer Sands (Cunningham, Britt, and Boatwright) ranges from 12,500 feet to 15,500 feet and have an average permeability range of 0.1 to 5.0 md. This evaluation includes several components.Well production history matching and pressure analyses are used to determine effective fracture length. Results of these analyses are compared with calculated values based on laboratory generated cleanup data for the two fluid systems. Flowback rate, pressure, accumulated volume, viscosity, and polymer content were collected following the fracture stimulation treatments.The fluid systems compared in this study are a conventional low polymer system with gel breakers and a new, low molecular weight polymer system that requires no breakers. Both fluids use borate cross-linking chemistry. The low molecular weight fluid system creates transient, high molecular weight polymer chains at higher pH conditions. After exposure to the formation minerals, the pH drops and it reverts to a clean, nearly Newtonian, low viscosity fluid that causes little conductivity damage.The results of this study show that the use of low molecular weight fracturing fluid provides significant improvements in the effective fracture length over conventional low polymer fracturing fluids. Simple engineering tools have also been developed to evaluate both fluid and proppant selection and job design to achieve improved well performance. It also demonstrated that improved recovery of the fracturing fluid can be achieved at excellent rates without the use of conventional gel breakers.

Empirical Modeling of the Viscosity of Supercritical Carbon Dioxide Foam Fracturing Fluid under Different Downhole Conditions

“…Hydraulic fracturing of shales is a technique that is widely known to unlock these stored reserves [3] and the fracturing fluids that are commonly used are polymer-based aqueous solutions. However, the application of polymers can plug the nanopores, which becomes a crucial issue [4][5][6][7][8][9]. Moreover, the fracturing process requires a high amount of fresh water during its application, it is susceptible to formation damage in water-sensitive regions, and it provides a reduction in liquid recovery [7,9].…”

Viscosity Models for Polymer Free CO2 Foam Fracturing Fluid with the Effect of Surfactant Concentration, Salinity and Shear Rate

“…The proposed equations for K and n are given below. Substituting values of K and n in Equation (1) gives a new and modified form of power law model, which incorporates the effect of dimensionless concentration and shear rate, and is given by Equation (6).…”

“…The parameter estimates of this equation are available in Table 3. Viscometric data of foam was compared with the predicted viscosity values using Equation (6). R 2 and RMS values for this model was Substituting values of K and n in Equation (1) gives a new and modified form of power law model, which incorporates the effect of dimensionless concentration and shear rate, and is given by Equation (6).…”

“…The parameter estimates of this equation are available in Table 3. Viscometric data of foam was compared with the predicted viscosity values using Equation (6). R 2 and RMS values for this model was appeared to be 0.999 and 4.8, respectively.…”

“…These huge reserves are unlocked by fracturing shales [5]. When the shales are fractured using conventional aqueous based polymer solutions, the plugging of nanopores takes place [6][7][8][9][10][11]. These conventional fracturing fluids need high amount of fresh water, increases the formation damage especially in the water sensitive zones and decreases the liquid recovery [9,11].…”