Oil- and gas-exploration and production companies searching for commercial production have been required to venture deeper into the earth’s crust and consequently have been forced to contend with hotter working temperatures and higher pressures. These conditions have become commonplace in that the companies operating under high pressures and high temperatures have been contending with these conditions on a near-daily basis for the past two to three decades in North America, depending on their region of operation.
A brief history of south Texas is provided in this paper, along with a geologic description of several formations, such as Vicksburg and Wilcox sandstones. In addition, this paper discusses the different types and methods of laboratory testing necessary for the preparation of hydraulic fracturing and discusses perforation schemes typical to the different regional areas. Included are field examples of hydraulic-fracturing treatments that were performed under high-pressure, high-temperature (HPHT) conditions (>300°F [>150°C] and >10,000 psi working pressure or a pore-pressure gradient >0.8 psi/ft). Other topics that will be discussed are wellhead equipment, such as wellhead isolation tools and frac valves, fracturing equipment types and amounts, the proper application of stimulation "iron" (2-in. 1502 and 3-in. flanged connections), and fracturing materials for gelling, crosslinking, non-emulsifying, and effectively propping hydraulic fractures at high temperatures. Also explained are the pump-in tests and diagnostics that are performed to help service companies and operators deliver a safe and effective method for HPHT hydraulic fracturing on a consistent basis.
This paper is intended to provide a better understanding of the many components that need to be addressed when preparing for a HPHT treatment so that operators can apply these components to any field anywhere in the world.