Directional Drilling Drag Back Process Mechanics Analysis

Directional drilling drag back process is the one of the most important step in the directional drilling construction, this article take back the drag force value forecast and pipeline back to drag pipe mechanical properties analysis in the process of the two starting points for research, for the design of the pipeline crossing river technology provides important theoretical support.Forecast back to drag force is one of the focus in the study of horizontal directional drilling technology, can be through the project plan design, drill pipe stability evaluation in the process of model selection, construction, and back to drag drag reduction technology provide strong evidence for such important link, because ignores some influence factors in the process of calculation or introducing experience parameters, makes the existing back drag prediction method of forecast accuracy and low reliability, difficult to meet the needs of the practical engineering. This article system in-depth study dragged back stage back calculation method of the theory of drag force, and through the project example data evaluated in this paper, the optimization of drag force calculation method of the accuracy and reliability.Then close to the engineering project example model is established using the finite element software, forecast back to drag the process piping stress analysis, based on the above research results put forward through the construction of the influence of the parameters on the calculation of pipe stress are studied.The main research contents and conclusions are as follows: construction of oil and gas pipeline crossing project specification method, water supply and drainage pipeline engineering construction standard, unloading arch earth pressure calculation method, the net buoyancy calculation method, capstan calculation method, method of American material experiment society ASTM, American gas research method for the application conditions and the applicable scope of each specific instructions, and the various differences that exist in the formula calculation results to make a detailed explanation. Theoretically clarify the advantages and disadvantages of each theory formula, in the final analysis the optimization formula for computing the drag force value calculation method for the winch; Then using finite element software to simulate the actual engineering construction, observe the pipeline back into tow stages in different physical parameters(pipeline yield strength and elastic modulus, poisson’s ratio, density of tubing, clay density, soil elastic modulus, poisson’s ratio) under the influence of pipe stress changes, so as to analyze the influence of different parameters on the pipeline stress situation; Finally, we will be seven back to the theory of drag force formula into the main gas pipeline in the actual engineering, verify the previous theoretical analysis it is concluded that the calculation method of the capstan closest to the actual calculated results back to the drag force construction value.