Research On Optimal Design Of The Horizontal Well Trajectory In Multi-Well Pad

As domestic shale gas exploration and development strength increasing,the development mode of multi-well pad is considered to be a best model because it can shorten well construction period,reduce drilling cost and improve the efficiency.Because he relative concentration of the horizontal well in multi-well pad,the majority of horizontal wells are designed for 3D horizontal well,trajectory design difficulty and its effect on the drilling cost and risk are very obvious.So it is very important to optimize horizontal trajectory in multi-well pad.By analyzing the characteristics of horizontal wells in multi-well pad,determine the three-dimensional and three building model of the horizontal well as general form in multi-well and write batch design program of the horizontal well.On this basis,the paper analysis the composition of the drilling cost for horizontal wells in multi-well pad,this paper presents a method to calculate the cost associated with the drilling time and costs associated with well construction and formed the drilling cost prediction method,the preparation cost prediction program of horizontal well.Based on the drilling cost,drilling risk problem of the horizontal well in multi-well pad is evaluated,the calculation method of risk coefficient of wellbore instability by the safe density window of drilling fluid is proposed to solve the problem of wellbore stability;aimed at the problem of friction and torque we use the friction torque overload risk factor evaluation of wellbore stability.Based on the drilling cost and risk evaluation,Carry out drilling cost and drilling risk evaluation the a series of trajectory of horizontal wells in multi-well pad under the condition of different parameters design based on the optimization principle can be screened out the most suitable wellbore trajectory.Based on research of theory and methods,Paper with a include four horizontal wells trajectory design in multi-well pad as an example,this paper expounds the horizontal well borehole trajectory of multi-well pad optimization design process and steps in detail,well trajectory design is reasonable,reliable result finally to optimal design of the horizontal well Trajectory in Multi-Well Pad has a certain theoretical guiding significance.