Fracture-Stimulation Placement With Fiber-Optic Distributed-Sensing Diagnostics
Authors: Carpenter Chris 
Published: August 2016

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 173348, “Challenging Assumptions About Fracture-Stimulation-Placement Effectiveness With Fiber-Optic Distributed-Sensing Diagnostics: Diversion, Stage Isolation, and Overflushing,” by Gustavo A. Ugueto C., Paul T. Huckabee, and Mathieu M. Molenaar, Shell, prepared for the 2015 SPE Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA, 3–5 February. The paper has not been peer reviewed.

The connection of the wellbore to hydrocarbon-resource volumes by effective fracture stimulation is a critical factor in unconventional-reservoir completions. This paper provides some insights into the effectiveness of the hydraulic-fracture-stimulation (HFS) process with fiber optics (FO), distributed acoustic sensing (DAS), and distributed temperature sensing (DTS). The paper discusses multiple wells where FO has been used to gain a better understanding of three highly debated fracture-stimulation-distribution topics: diversion, stage isolation, and overflushing.

Introduction

Optimization of the connectivity/distribution process in HFS requires a balance between capital investment to “compartmentalize” the wellbore and the incremental rate of economic return associated with well performance results. Perforation-cluster efficiency from cemented plug-and-perforate (CPP) completions in unconventional horizontal wells typically ranges between 68 and 79%. Isolation and controlled placement of stimulation volumes within stages for uncemented packer-and-sleeve (UPS) systems are of concern. There are multiple reasons for these inefficiencies. A complex interplay between reservoir-quality variability, well placement within the stratigraphy, effective fracture geometries, lift efficiency, and the effectiveness of HFS treatment ultimately controls the performance of any given well. FO and other diagnostics demonstrate the dynamic nature of the stimulation placements and provide further insight into and quantification of stimulation-distribution effectiveness. Diagnostics and field trials also indicate that improved practices and new completion technologies are emerging that can improve the effective-stimulation distribution.

Diversion

There is a renewed interest in the use of diversion techniques to improve the efficiency of HFS. Applications vary from refracturing to improving perforation- cluster efficiency. Traditionally, diversion has been evaluated with very limited diagnostic data and is heavily dependent on pressure response observed during pumping operations. In most cases, the effectiveness of diversion has been measured ultimately by an increase in production relative to what are considered “like” wells. While this approach is valid, inherent variability in production results between nearby wells caused by reservoir quality makes the comparison very difficult. In addition, obtaining conclusive answers on the basis of production performance can take a relatively large number of wells and a significant amount of time. FO, in combination with other complementary completion diagnostics, can provide a way to shorten the time and reduce the number of wells required for evaluation of the effectiveness of diversion technologies. Furthermore, diagnostics provide information required to fine-tune deployment procedures. The complete paper provides examples of FO-diagnostics results for one type of diversion technique (biodegradable particulate diversion).