Development of Hydraulic Fracturing Evaluation Techniques Using Chemical Adsorption Mechanics

Abstract

ABSTRACT: In order to identify problems during the fracturing job and optimize the hydraulic fracturing design for future development, an effective method for monitoring and evaluating the hydraulic fracturing operation is needed. Due to the complex nature of the process, most of the existing techniques for hydraulic fracturing diagnostics and evaluation are limited. In this research, a direct far-field measurement method was also developed in this research by utilizing chemical adsorption mechanics. A specially designed surfactant was tested in laboratory experiments for its ability to adsorb on the fracture surfaces. The advantage of this method is it can bypass the difficulties of assuming the fracture geometry and directly translate the fracture surface area into stimulated reservoir volume (SRV). It will be especially useful in naturally fractured reservoirs, where the hydraulic fracture will interact with the existing natural fractures. A dynamic adsorption model was developed for the proposed evaluation method in field scale. Furthermore, a hydraulic fracturing efficiency improvement method was proposed using the same surfactant. An economic analysis was conducted using the comprehensive hydraulic fracturing model developed in this research. The results showed that the efficiency of hydraulic fracturing could be significantly improved using surfactant adsorption. 1. INTRODUCTION Hydraulic fracturing is a process that could improve the recovery of hydrocarbons from formations, especially for low permeability formations. A successful hydraulic fracturing operation is the key to enabling economic production from low permeability reservoirs. Because of lacking affordable data acquisition technologies during the operation, it has been a "black-box" tool for the industry for decades, although many researchers have tried to measure or numerically describe the hydraulic fracturing process (Warpinski et al., 1994; Cipolla & Wright, 2000). One of the reasons for this situation is the difficulty of verification. The actual fracture geometry that is located at extreme in-situ conditions thousands of feet under the surface is nearly impossible to obtain directly. Another reason is that the whole process is extremely complex. A poorly designed operation or problems during the fracturing job, such as inadequate fluid volumes, inappropriate proppant selection, and insufficient treatment stages, would result in a less efficient fracture network, contributing to the flow in the production phase (Sinha & Ramakrishnan, 2011). If no proper evaluation techniques were deployed during the fracturing operation, operators could not realize the underperformance of the well until it had been put into production for a while. Since then, a workover or re-fracturing job has been needed to optimize production, which would cause a considerable amount of extra cost and an enormous amount of non-productive time (NPT).