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

摘要

As producing companies search for significant hydrocarbonrnresources, it has become necessary to pursue opportunities inrnfrontier geologic horizons and geographic locations. Thisrnpursuit frequently results in encountering High Pressure –rnHigh Temperature (HP/HT) environments. The petroleumrnindustry defines HP/HT wells as those exceeding 10,000 psirnand 300°F.rnSeveral companies have drilled into HP/HT horizons in thernCalifornia San Joaquin basin over the past 30 years, butrngenerally operations were halted due to equipment limitationsrnor due to limited hydrocarbon indications. In late 1998, arnsignificant gas flow was identified from the Temblorrnformation at depths below 17,100 ft, with geologicrninformation indicating a potential Temblor sand grossrnthickness of up to 3600 ft.. The pressure design basis forrnsubsequent wells assumed an estimated equivalent porernpressure of 16.9 ppg. This information and other producingrnconditions, indicated potential bottomhole conditions of 425°Frnand 18,000 psi. Produced fluids also indicated the presence ofrnhydrogen sulphide (H2S), which, at these pressures, dictaternsour service metallurgical specifications.rnThese potential extreme well conditions required veryrndetailed completion engineering design, equipmentrnqualification, rigorous planning, and precise field execution tornachieve successful well completions. This paper will detailrnand discuss the well completion design basis and issues;rnequipment/perforating limitations and qualification tests,rntubular stress and loading analyses, high-density completionrnbrine usage, and actual field operational experiences.rnNumerous contingencies were planned in detail, some ofrnwhich had to be implemented. The most significantrncontingency operation was a high pressure coiled tubingrnmilling operation to clean out 2500 ft of formation andrnperforating debris, which plugged the tubing string.