Completion Design and Implementation in Challenging HP/HT Wells in California

Abstract

As producing companies search for significant hydrocarbon resources, it has become necessary to pursue opportunities in frontier geologic horizons and geographic locations. This pursuit frequently results in encountering high-pressure/high-temperature (HP/HT) environments. The petroleum industry defines HP/HT wells as those exceeding 10,000 psi and 300°F.Several companies have drilled into HP/HT horizons in the California San Joaquin basin in the past 30 years, but operations were generally halted because of equipment limitations or limited hydrocarbon indications. In late 1998, a significant gas flow was identified from the Temblor formation at depths lower than 17,100 ft, with geologic information indicating a potential Temblor sand gross thickness of up to 3,600 ft. The pressure design basis for subsequent wells assumed an estimated equivalent pore pressure of 16.9 lbm/gal. This information and other producing conditions indicated a potential bottomhole environment of 425°F and 18,000 psi. Produced fluids also indicated the presence of hydrogen sulfide (H 2 S), which, at these pressures, dictates sour service metallurgical specifications.These potential, extreme well conditions require a very detailed completion engineering design, equipment qualification, rigorous planning, and precise field execution to achieve successful well completions. This paper details and discusses the well completion design basis and issues, equipment/perforating limitations and qualification tests, tubular stress and loading analyses, high-density completion-brine usage, and actual field operational experiences.Numerous contingencies were planned in detail, some of which had to be implemented. The most significant contingency operation was a high-pressure coiled-tubing milling operation to clean out 2,500 ft of formation and perforating debris that plugged the tubing string.

Explaining thermal failure in saturated clays

“…Such structures are often part of emerging technologies, including energy storage in soil using geostructures such as piles, walls and slabs for environmentally friendly heating and cooling of buildings (Brandl, 2006;Laloui et al, 2006). Another emerging technology involving thermally affected soil masses is oil recovery from reservoirs that are at high pressure and high temperature (Hahn et al, 2003). Finally, in the design of underground nuclear waste disposal facilities, which have been in development for several decades, the effects of temperature are invariably considered as a principal factor (e.g.…”

HPHT Well Basis of Design Case Study: Offshore Thailand Advanced Tubular Analyses Experience

“…The state-of-the-art thermal simulation with stress modeling analyses, which combines the effects of transient temperatures and pressures, is particularly important when associated with the HPHT well-design process (Hahn et al 2000(Hahn et al , 2003. Simulation would initially involve the investigation of the changes in pressure and/or temperature that occur over the life of the planned well and would subsequently include further study how these changes would effect each of the casing stresses, casing buckling, tubing movement, tubing buckling, triaxial stress, and packer loading, whichever is applicable.…”