Research On Geometric Simulation Method Of Side-drilled Window In Coiled Tubing

Coiled tubing sidetracking windows is a very important means to enhance oil and gas recovery during oil exploration and development,and also to increase oil and gas production capacity.This technology has less investment and high economic efficiency,not only can shorten the drilling process cycle,but also can save the cost of drilling operations.In the process of drilling the window side of the coiled tubing,the shape of the window will affect the passage of the tool and the success rate of the target.If the window is unreasonable,it will inevitably make it difficult for the tool to pass through the window,and it may not be able to smoothly control the wellbore trajectory.Of course,it will not be able to target a series of problems.Therefore,a reasonable window shape facilitates the passage of the coiled tubing,avoids multiple trips,and is also beneficial to the mid-target rate of sidetracking.In order to study the shape of the window in the sidetrack window,this paper summarizes the development status of the sidetrack drilling window for coiled tubing at home and abroad,and finds that there are many literatures on sidetrack windowing,but there are few studies on the shape of the sidetrack window.Many researchers have studied the shape of the sidetrack window in a two-dimensional plane.On the one hand,this only results in the shape of the incision in the casing of the windowing tool.It is impossible to know the situation where the tool extends beyond the outer part of the casing.The pass rate and rationality of the window are determined;on the other hand,the shape of the tool also has a certain influence on the formation of the window shape.In order to more accurately study the shape of the sidetracking window,this study uses a three-dimensional model.This article first determines the parameters of the coiled tubing windowing tool.For the characteristics of two types of single-angle and multi-angle tilters,multi-angle tilters were selected for study,and the height and angle of each section of the slope were set.According to the design requirements of the milling shoes,the selection of the milling shoe combination was made.This paper proposes to choose a double-milling shoe combination for research,among which the leading shoe is a diamond-milled shoe,the reamer-milled shoe is a hard-alloy mill,and the relevant parameters of the milling are set.Second,establish a three-dimensional model to study the intersection of the shoe and the bushing.A simple model of two rotating bodies—cylindrical plane and cylindrical plane intersecting diagonally to study its changing rule,and the geometric simulation algorithm for the intersection of the two models are designed.In order to solve the results of the model intersection,the following steps of algorithm design are made: the establishment of three-dimensional mesh model,the intersection point between the triangular elements,the classification of the intersection points and the data structure,the distribution of the intersection points in the triangle elements,and the intersection triangle elements.Subdivision,edge determination,invalid surface deletion algorithm,model reconstruction,etc.Then,a two-dimensional schematic diagram of the sidetracking window is established,including the relationship between the contact of the milling shoe with the leaner and the casing,and the relevant calculation formula is deduced through the geometric relationship to study the trajectory of the shoe during the sidetracking process in the case of rigidity and Its change of azimuth along the horizontal direction.Finally,using the two-dimensional model and related examples to calculate the shape of the window and analyze the results,pointed out the shortcomings of the method.Then use the three-dimensional model,using the geometry simulation algorithm designed in the previous study window shape.Because the number of model grids is too large and the program’s algorithm for grid processing is not optimized,the calculation time is too long.Therefore,the three-dimensional model is simplified to replace the three-dimensional model of the shoe-making and casing,and relevant examples are calculated to verify the feasibility of the algorithm.