Improvement of BOP Sealing Systems Is an Urgent Requirement for HP-HT Deep Wild Well Control

Abstract

Abstract A recent high pressure and temperature wildcat well control operation of the Hungarian National Oil and Gas Co. on a 4 239 m /13,907 ft/ deep well required 46 days up to capturing in closed cooperation with numerous major and service companies. The operating shaft damage of a BOP caused the blowout. Up-to-date technologies and materials, among others sophisticated elastomers were introduced because of the extremely severe conditions. The wellhead temperature exceeded 150 deg. C / 300 deg. F/, the flowing pressure varied between 36 and 48 MPa /from 5100 to 6900 psi/, and the produced fluids were aggressive-gas contaminated, superheated brine water, i.e. steam. The sealing elements of the recommended BOP failed to work after 48 hours service, thus jeopardizing the specially designed snubbing operation. On the basis of- the case history, the conclusion of the paper calls for improvement of /1/ the wellhead equipment and blowout preventer systems, /2/ the achievement of harmony in the field of sealing elastomers and the employment of metal-to-metal seals and /3/ proper selection of elastomer formulations on the basis of environmental agents. The above three are the preconditions of successful wild well control operations. Introduction The petroleum industry is one of the most highly hazardous industry branches. Since the zero-risk situation can not be achieved, suitable structural materials and technologies reduce the expenditures. The continuous development is a basic criterion of the deep drilling activity especially because of the aspects of blowout prevention. The evaluation of blowouts and related killing and controlling operations has primary importance concerning the directions of developments. During capturing jobs it frequently occurs that in other cases good elastomers break down although it is a fact that the demands are more severe than normally. The risk of hydrocarbon exploration in Hungary extremely high because of the abnormal geo-environmental conditions. A recent blowout and the operations aiming at the killing of the wildcat well justified that the elastomers were excellent multipurpose sealing materials but not for all the possible combination of loads. P. 659^