Advanced Technology Solutions for Next Generation HPHT Wells
Authors: Payne Michael Lyle , Pattillo David , Miller Richard , Johnson Carl Kenneth 
Published: February 2016

Abstract
This paper describes research efforts and technology development associated with the next generation of high pressure, high temperature (HPHT) well designs. Sometimes referred to as x-HPHT (extreme HPHT), work has been ongoing for several years looking at the next generation of HPHT wells for both subsea and shelf/onshore operations. A large number of challenges arise when addressing the engineering of HPHT wells. This paper will not attempt to cover all such topics but will focus on some critical technology areas which underlie key well design and planning issues. In depth discussions are specifically provided on advanced material testing and qualification, heavy load handling, and high temperature electronics. BP is at the forefront of many of these technologies and is working with industry partners to advance capabilities and assurance in these areas.

Introduction
The next generation of HPHT wells includes full 15 ksi subsea wells as well as preliminary engineering for 20 ksi subsea wells. For shelf and onshore applications, the trend of deep drilling for new gas reserves has raised requirements for 20 to 25 ksi surface pressures. Several classes of wells constitute the future of xHPHT operations. One class involves deep oil plays in deepwater operating environments. A second and distinct class involves deep gas plays on shelf or onshore environments. There are both common challenges and distinct problems between these two classes of xHPHT wells. The technology challenges associated with combining the ultra-high pressures of deep gas with the deepwater environment are beyond the foreseeable future at this time.
Despite the various challenges of xHPHT, reserve forecasts accompanying these deep horizons are high. The industry is thus compelled to address these technical challenges in order to pursue future reserves and production. Extreme HPHT trends can be seen in the Middle East, Far East, China, Indonesia, Former Soviet Union, and North American operating regions. Thus, xHPHT technology will enable development of new hydrocarbon resources on a global basis.

HPHT Well Classifications
Currently, less than 1% of all wells drilled in the USA have penetrated below 15,000'. Despite this statistic, deep reservoirs defined as production below 15,000' account for 7% of domestic production. This speaks to the prolific production rates and large reserves which accompany successful exploration and development of these deep horizons. The National Petroleum Council projects this share will need to grow to 12 percent by 2010 to ensure that the US demand for natural gas is met. Longer term, the deep gas resource in the US is forecast to be enormous: about 29 percent of the Nation's ultimate potential gas resource is deep gas. Under such challenging conditions however, only the most promising deep prospects are economic to drill because of the high risks and costs entailed in deep drilling. The cost of drilling and equipping the average deep gas well (17,400') is about 12 times that of the average Lower 48 onshore gas well drilled to 6,000'. Industry experience has also shown that with an ultra-deep well, the last 10 percent of the bore hole can account for 50 percent of the well's cost.
Figure 1 shows one classification scheme for HPHT wells. In this case, HPHT wells are initially identified as having bottom-hole pressures above 10 ksi and temperatures above 300° F (~150° C). This HPHT classification would include wells up to 15 ksi and 350° F (~175° C) as shown. Ultra-HPHT wells are the next class and involve pressures up to 20 ksi and 400° F (200° C). The final class shown is Extreme HPHT (xHPHT) and involves wells up to 30 ksi and 500° F (260° C).