Improving Well Completions by Use of Real-Time Microseismic Monitoring: West Texas Case Study
Authors: Denney Dennis 
Published: February 2015

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 137996, ’Improving Well Completion by Use of Real-Time Microseismic Monitoring: A West Texas Case Study,’ by E.A. Ejofodomi, SPE, M.E. Yates, SPE, R. Downie, SPE, T. Itibrout, SPE, and O.A. Catoi, Schlumberger, prepared for the 2010 SPE Tight Gas Completions Conference, San Antonio, Texas, 2-3 November. The paper has not been peer reviewed.

Hydraulic-fracture-stimulation treatments that were performed on a vertical-well completion in the Spraberry/Wolfcamp formations in Midland County, Texas, are reviewed. Real-time microseismic hydraulic-fracturing monitoring (HFM) was used to “track” development of the hydraulic fractures as they propagated through the formation, thereby allowing implementation of corrective actions to improve the completion efficiency of the well.   

Introduction

The “Wolfberry play” is the local name given to wells with commingled production from the Wolfcamp through the Spraberry formations. This low-permeability oil play extends over 2,500 sq miles in 11 counties in the Midland basin of west Texas. Typical porosity and permeability ranges for the Spraberry are 5 to 18% and 0.01 to 3.0 md, respectively. With new hydraulic-fracturing technologies developed in the late 1980s, operators in the basin began to explore and develop the potential of the deeper Wolfcamp interval. The trend contains pockets of high porosity and permeability, but most of the reservoir interval is lower quality, with porosity and permeability ranges of 5 to 8% and 0.001 to 1.0 md, respectively. By identifying and completing the productive Wolfcamp trend in addition to the Spraberry, operators have reduced payout times and increased returns on investments.

In recent years, HFM has become relied upon to understand the propagation behavior of stimulation treatments. This technology enables the quantification and evaluation of the induced fracture. It also has been vital in observing and analyzing the interaction or communication of the created hydraulic fractures with potential geohazards such as faults and natural fractures.

In this study, the operator evaluated the effectiveness of typical Wolfberry-completion designs and practices. Thus, in addition to use of good petrophysical and rock-mechanical properties for the completion and fracture design, real-time microseismic HFM was used to obtain information about the fracture length and height to improve the fracture model, validate stress profiles, and determine the major fracture orientation for future well spacing and infill-drilling programs. The real-time application of microseismic HFM identified unwanted fracture behavior and enabled making necessary modifications to optimize the overall well completion.

Wolfberry-Completion Considerations

Typical Wolfberry wells penetrate up to 3,000 ft of gross interval. Typically, the wells are completed with five to ten fracture-stimulation stages during which a single or multiple wireline runs are made into the well to perforate and then isolate between stages. Each stage can have up to seven pay targets. While the best method of stimulating each zone is selective pinpoint perforation and stimulation of individual pay targets, this technique can prolong the overall completion time severely, and increase the well-completion costs. To ensure coverage of the stimulation treatments over the target intervals and manage completion costs, operators rely on two main perforation strategies—conventional limited-entry and single-cluster.