Abstract:
More than 80% oil and gas wells in Tarim Oilfield are ultradeep wells.With the proceeding of exploration and development, more and more horizontal wells are drilled, and drilling risk and complex situation treatment difficulty are increased correspondingly.Different drilling companies take different measures to deal with the complex situations, such as overflow, circulation loss, high concentration H
2S, pipe sticking, drilling tool breaking and high casing pressure.And there is successful experience as well as painful lessons.In Well 10HC of Middle Paleozoic, for example, a series of practical technologies and measures were taken to deal with the complex well situations, including drilling complexity treatment, drilling fluid technology, drifting technology and logging technology.It is indicated that blowdown and bottom exploration operation can provide plenty of useful information for the subsequent operation.The technologies and measures adopted after the circulation loss in return are vital to the subsequent operation, for complexity treatment difficulty will be increased and new complex situations may be resulted in if the circulation loss in return is not treated appropriately.It is favorable for the subsequent operation by injecting reversely a certain amount of drilling fluid quickly after the circulation loss in return to carry the suspended cuttings into the formation.It is demonstrated by many practical operations that this technology is of strong applicability and can provide the reference for the treatment of complex wells with similar situations.