Study On Key Drilling Technology Of Zhong 1-10-X8 CBM Cluster Well In Liupanshui Area

Liupanshui is located in the west of Guizhou Province,which is rich in coal and CBM resources.The coal seams in this area are large in number,thick and stable in distribution.The coal seam cleats are well developed and permeable.It is easy to exploit CBM.It has great development value and energy efficiency.Because of the influence of geological conditions,cluster wells are often used to exploit coalbed methane in this area.Cluster wells have the advantages of saving site and engineering costs,facilitating unified fracturing and common relief and drainage,and high overall development efficiency.This well takes Zhong 1-10-X8 well as an example to study the key drilling technology in order to achieve the purpose of high efficiency,safety and economy.This paper mainly studies the trajectory design and control technology of CBM well Zhong 1-10-X8 in Liupanshui Coalfield.The well structure,track and trajectory of the well are designed and calculated by means of theoretical analysis,experience reference and simulation calculation.The geological model and trajectory curve model of drilling target area are established by using CAD FLAC3D and Origin software.And the trajectory is optimized by MATLAB.According to the characteristics of coalbed methane cluster wells and the inclination tool selected,the technical means of trajectory control of subsection wells are formulated.The influencing factors and trajectory control mechanism of borehole trajectory are analyzed by finite element method.Through theoretical analysis and field test,the drilling fluid performance parameters of Zhong 1-10-X8 well in different sections are studied.The main conclusions are as follows:(1)The trajectory is optimized by means of MATLAB optimization toolbox.The results show that the shortest trajectory can be obtained when the vertical depth isV1 = 167.98m,?=26.92°,and K?= 3.23°/30m,which can save drilling cost and achieve the purpose of optimizing trajectory.(2)The main factors affecting wellbore trajectory are the soft and hard interbeds of rocks.The deformation of the lower BHA is the lateral force of the bit and the enlargement of the borehole diameter.(3)DrilIing fluid density is between 1.03-1.08g/cm3;viscosity is between 36-45s;mud cake is between 0.5cm;PH value is 8;sediment content is between 0.1%-0.2%.It effectively maintains wellbore stability and achieves the goal of safe and efficient drilling.The research results can be used for reference in drilling construction in similar areas.