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Yang G.,Research Institute of Drilling Engineering | Li Y.,Research Institute of Drilling Engineering | Zhou C.,Research Institute of Drilling Engineering | Ma C.,Research Institute of Drilling Engineering | And 2 more authors.
Drilling Fluid and Completion Fluid | Year: 2014

Drilling through the Nadu Formation in Baise Basin encountered severe borehole instability in the presence of high geostress in the micro bedding fissures and fractures developed formation. Wells drilled without borehole instability were always those with well angles less than 35°, while wells with deviations greater than 35° invariably encountered borehole instability in drilling the Nadu Formation. Mechanism behind which borehole instability took place in the Nadu Formation was studied, and downhole troubles in the second interval of Well KXH, the first unconventional horizontal well in this area penetrating the Nadu Formation, was introduced. Field operation in the past has demonstrated that water base drilling fluids cannot prevent borehole instability from happening in drilling the Nadu Formation whenever the hole angle is greater than 35°. The success of drilling the Well KXH is ascertained to the use of oil base drilling fluid, with environmental issues settled. The use of oil base drilling fluid paves the way for successful horizontal drilling in the future in this area. ©, 2014, North China Petroleum Administration Drilling Technology Research Institute. All right reserved.

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