Technology Research On Improving Drilling Speed And Gas Reservoir Protection In Wangfu Area

The Wangfu fault depression is located in the south of Songliao Basin. The gas reservoir development in this area has been to the preliminary period at present. The problems here are:the rock of lower formation, whose geological structure is complicated, is strong heterogeneity. At present when drilling the target layers the main chosen drilling head is roller cone bit which is a kind of low drilling-rate bit. To increase the drilling speed is affected with it. And there are no basic data about three-pressure profile and reservoir sensitivity evaluation in this area can be taken to protect the oil-gas reservoir and optimize the drilling engineering design.The paper is started with the research on basic mechanical characteristics and physical parameters including the rock mechanics strength, elasticity modulus, Poisson’s ratio etc of the rock surrounded by different lower formation. With the above research and the established well-logging interpretation, we find out the rock drillability of lower formation and the cone bit &the PDC bit drillability. Then we correct the theoretical results by experiments. At last this paper gives a proposal for optimizing the drill bits.Also the paper analyses the micro-component, micro-structure, sensitivity, influence of fluids on the microstructure of the reservoir rock with available basic geology data. These analysis results are: 1) the stress sensibility and acid sensibility of the rock of lower formation is strong. 2) we establish the three-pressure profile and quantify the equivalent density of pore pressure, collapse pressure and fracture pressure by analysing the well logging data and geology data of W2.By the research on the experimental& theoretical analysis of the rock hardness and drillability, sensitivity and three-pressure profile of the rock of lower formation, we give the rock drillability profile of lower formation, sensitivity and choice of sealing characteristics of drilling fluid. And the achievements have important significance on drill bit selections in this area and reservoir protection.