In its latest Monday note, energy research company Douglas-Westwood wrote that the Exploration & Production industry (E&P), experiencing rising global hydrocarbon demand as well as rising costs, is facing the technical challenge of the development of High Pressure – High Temperature (HPHT) reserves. HP / Extreme HP typically refers to borehole pressures between 10,000 - 20,000 psi; HT / Extreme HT refers to borehole temperatures between 300-400 ˚F (149-204 ˚C). Pressures and temperatures outside these ranges are referred to as “Ultra-HPHT”, which represents the absolute limits of current technology.
HPHT issues are not new; Schlumberger’s quarterly publication Oilfield Review examined HPHT issues in 1998 and again in 2008. But as a team from Baker Hughes noted in a 2013 paper presented at the Society of Petroleum Engineers (SPE) Annual Technical Conference and Exhibition:
The growing global demand for hydrocarbons is challenging the oil and gas industry to explore and develop deeper and hotter reservoirs, pushing the boundaries of equipment capability beyond traditional High Pressure High Temperature (HPHT) limits into the Ultra-HPHT region. Ultra-HP/HT wells are currently being drilled in the Gulf of Mexico, on the shelf and in deep water. Many of these wells have a total depth of in excess of 30,000 ft, where reservoir pressures and temperatures approach 30,000 psi and 500°F. There are many technological challenges that must be overcome for downhole service and completion tools to operate successfully in the Ultra-HPHT environment.
|Schlumberger uses guidelines that organize HPHT wells into three categories, selected according to commonly encountered technology thresholds. Click to enlarge.|
While the HPHT term is widely used, Frank Wright from Douglas-Westwood’s Aberdeen office explains, pressure and temperature do not always correlate: in Thailand many wells have extremely high temperatures without correspondingly high associated pressures. The term HPHT is also commonly associated with the high value offshore markets despite the large market opportunity existing onshore. A good example is the Haynesville shale gas play where one E&P Company has completed more than 300 HPHT wells, he noted.
HPHT reservoirs drive new technology requirements in a number of ways. Examples include:
Drilling in HP reservoirs necessitates heavyweight drill pipe (HWDP). HWDP can be at the upper limits of the shear rams on older BOP stacks, which are intended to cut through pipe in an extreme well control event.
High temperatures also have an impact on directional drilling where some types of drilling motors rely on polymer sealing elements which have temperature limitations. New material formulations have come to play in this specific area.
To meet the HPHT challenge, there is collaboration within the industry, as in BP’s Project 20K (earlier post) (targeting technology capabilities to support conditions of 20,000 psi and 300 ˚F), and within the R&D departments of the Oilfield Services (OFS) companies.
The ability to develop new tools and services for the most extreme wells is increasingly viewed as a unique competitive differentiator, Wright suggested. OFS companies are thus working on a suite of technologies including Logging-While Drilling (LWD) tools, & Perforating Guns that can function reliably in ultra-HPHT reservoirs.
Guijun Deng, James Doane, Antonio Ruffo, Goang-Ding Shyu, Scott Collins (2013) “Design Verification, Optimization and Validation of Ultra-HPHT Completion and Production Tools” SPE 166231