Safe and high-efficiency drilling technology for horizontal sections of shale gas wells in Well Block Zi-201

Abstract:

Well Block Zi-201 is a key shale gas exploration and development area invested by PetroChina in the Rongxian area， Zigong city. Drilling of horizontal sections in this well block encountered many engineering challenges， mainly including serious borehole sloughing， hole instability， difficult well path control， low intersection rate of high-quality reservoirs， frequent sticking while tripping， which seriously restricted drilling safety and efficiency. In view of the above problems， the non-stabilizer mud moter was selected to optimize the BHA for reduction of the rigidity and friction of the BHA. At the same time， the compound plugging agent with plastic deformation particles and rigid plugging materials has been developed to improve the density， and strengthens the well wall support and sealing characteristics of the oil-based drilling fluid so as to ensure drilling safety and efficiency in the horizontal sections， and realize the normal completion of horizontal wells in Well Block Zi-201. Moreover， compared with previous drilling， the drilling period has been reduced by 34.12% with the effective intersection rate in high-quality reservoirs up to 100%， which provides a reference for safe and efficient drilling in the block and lays a foundation for increasing explored reserves and production.