Case Study: Application of a Viscoelastic Surfactant-Based CO2-Compatible Fracturing Fluid in the Frontier Formation, Big Horn Basin, Wyoming

Abstract

fax 01-972-952-9435.Abstract CO2 based fluids are commonly used to fracture stimulate formations with low reservoir pressure as well as formations that are more sensitive to water treatments (high capillary pressure, swelling clays etc). In particular, the Frontier Formation located in Bighorn Basin, Wyoming, has seen a variety of stimulation fluids used over the past years with varying degrees of success. When dealing with water sensitive formations, a common practice has been to use oilbased fluids. However, fluids of this nature can have detrimental effects on gas zones with low reservoir pressure and this might be the reason for erratic well performance of previously treated Frontier completions. It has also been determined that oil-based fluids can alter the reservoir wettability and hence cause formation damage. With this in mind and considering the environmental and economical benefits of using a water-based fracturing fluid, a novel viscoelastic surfactant based, CO2-compatible, high foam quality (>60%) fluid was proposed as the main fracturing fluid. This paper will discuss the first application of this visco-elastic based fluid on wells in Park County, Wyoming. This paper will discuss stimulation with the new fluid and how pin-point pressure measurement enabled the operator to make informed decisions to define fracturing/completion strategy. We also present the additional benefits of incorporating existing dipole sonic tool information to calibrate "in-situ" stress, Young's Modulus and Poisson's ratio. Finally, a production history match is conducted on wells treated with the new fluid.

Recent Advances in Viscoelastic Surfactants for Improved Production From Hydrocarbon Reservoirs

“…Wormlike micelles are dynamic structures that differ from polymer solutions in that the aggregates are constantly breaking and reforming, in contrast to polymer solutions, where the lengths of the chains are fixed at the point of quenching during synthesis (Cates 1990;Cates and Candau 1990). These micelles have been described as "living polymers" because of their dynamic nature.…”

“…This in turn has an effect upon the diffusion properties of the chains as well as the viscoelasticity. Micelle breakage is assumed to be a unimolecular process where the lifetime of the chain before breaking into two segments is given by the relaxation-time parameter s break (Cates 1990;Cates and Candau 1990):…”

“…In the limit when s break is much less than s rep , the VES solution behaves as a Maxwell fluid with a single relaxation time given by Eq. 2 (Cates 1990;Cates and Candau 1990):…”

Hydrolysis Effect on the Properties of a New Class of Viscoelastic Surfactant-Based Acid and Damage Caused by the Hydrolysis Products

“…In the recent decade, viscoelastic surfactants have been widely and successfully used in acidizing Zeiler et al 2004), acid fracturing Al-Muhareb et al 2003;Artola et al 2004;Bustos et al 2007;Fontana et al 2007;Bulat et al 2008), and hydraulic fracturing jobs (Samuel et al 1997). Usually, polymer-based acid systems will cause high friction pressures and formation damage because of residue precipitation, breakers are needed to enhance polymer degradation and make the flow back easier, and the cleanup time is lengthy.…”

Impact of Hydrolysis at High Temperatures on the Apparent Viscosity of Carboxybetaine Viscoelastic Surfactant-Based Acid: Experimental and Molecular Dynamics Simulation Studies

“…In recent years, viscoelastic surfactants have been successfully applied in oilfield acid fracturing fluids (Al-Muhareb et al 2003;Artola et al 2004;Bustos et al 2007;Fontana et al 2007;Bulat et al 2008), fluidloss pills ) and matrix-acidizing fluids Al-Mutawa et al 2005;Zeiler et al 2006;Liu et al 2009;Nasr-El-Din et al 2009a, b). VES-based fluids were used in these applications because, first, they can serve as substitutes to polymers as fluid viscosifiers.…”