20,000 psi Frac Applications using Composite Bridge Plugs
Authors: Fulks Jeff M. 
Published: October 2008

In certain completion operations, there is a need to sustain high frac pressures of up to 20,000 psi when completing a well. In order to meet this demanding requirement, a creative solution has been implemented. Field runs and lab testing have confirmed that composite bridge plugs are a viable option in these high pressure applications. The use of composite bridge plugs for these applications allows for a method of fracing a well that has cost benefits over traditional fracing methods.

Using composite bridge plugs for frac applications has become an industry norm. In applications where frac pressures exceed 12,000 psi, the use of composite bridge plugs has been limited. Unique fracing methodology using composite bridge plugs has been developed, allowing frac pressures to achieve and maintain 20,000 psi while maintaining the cost savings of running composite bridge plugs. This paper will review the methodology utilized to meet the rigorous requirements for these high pressure wells and the results of lab testing performed.

Introduction

The idea of using composite bridge plugs in high pressure fracing applications was presented by a production oil company. In order to achieve this, a system had to be developed to achieve and sustain high differential pressures across one or more composite bridge plugs. An existing, field and lab tested composite bridge plug was selected for the project. The FracGuard??composite bridge plug chosen is a high pressure, high temperature composite bridge plug which has been used in numerous well applications as well as long term tested in a laboratory environment to differential pressures of 12,000 psi at 400 °F. A 12,000 psi composite bridge plug was chosen over a 10,000 psi plug so there would be a safety factor built into the test, eliminating the possibility of a failure as the limits of a 10,000 psi plug would be approached and possibly exceeded in this test. The method chosen for this application was to use two 12,000 psi rated composite bridge plugs stacked to create a system capable of achieving differential frac pressures up to 24,000 psi.

Overview

FracGuard??composite bridge plugs were chosen for this application due to their ability to achieve and sustain high pressure differentials at elevated temperatures while also providing cost benefits over other tratidional fracing methods and tools. Other tools considered for this methodology were cast iron bridge plugs and permanent packers. Since permanent packers are presently not typically used in these scenarios, the focus was turned to bridge plugs, both cast iron and composite.

The advantage of using a composite bridge plug versus a cast iron bridge plug is its time efficient millability. A typical composite bridge plug has an average mill up time of approximately 20 minutes per plug, depending on the size of the plug, the method of milling and the specific wellbore conditions. The average mill up time of a comparable cast iron bridge plug is six to ten times longer than that of a composite bridge plug. Reducing mill up time can be a considerable cost savings.