Surface Area vs Conductivity Type Fracture Treatments in Shale Reservoirs

摘要

Hydraulic fracturing continues to be the primary mechanism to produce hydrocarbons out of the tight shale reservoirs. Ever since the success of Barnett shale program, operators are inclined to pump similar large volume water fracture treatments with little or no proppants in their respective shale plays. This assumes that all shale plays are the same and react accordingly to large volume treatments. The basic objective behind such treatments is to contact large surface area, which has been very successful in the Barnett shale play. Such large volume treatments in other shale plays may not be an optimized solution for the specific shale attributes and the response may lead to uneconomical production results. Some shales based on their reservoir characteristics might require a conductivity type fracture treatment. So, it is important to understand the characteristics of these shales before deciding the stimulation treatments. In addition to core and log analysis of these shales, fluid sensitivity tests, Brinell hardness tests, unpropped fracture conductivity tests and more importantly a Diagnostic Fracture Injection Test (DFIT) can help define the guidelines for choosing between a surface area and a conductivity type fracture treatment. Integrating the various data sources is important in arriving at these guidelines. The main objective of this paper is to provide these guidelines along with examples such that the costly trial and error approach for stimulating shales can avoided. Examples from both oil and gas shales namely, the Gothic, Haynesville, Eagle Ford and Barnett shale plays in the USA are included in this work.