Study On Optimal Design Of Long Horizontal Section Navigational Drilling

Long horizontal section wells have been widely used in the development of unconventional oil and gas reservoirs.However,conundrums like trajectory controlling in long horizontal section,steering tool pressure transferring,and poor hole cleaning which causes the forming of cuttings bed.In this paper,azimuth drift problem occurred in the process of long horizontal section navigational drilling and hole cleaning problem were studied.The study is significant for long horizontal section wells drilling optimization design,improving drilling efficiency,reducing downhole complicated conditions.Through indoor shale rock drillability experiment,combined with shale acoustic properties,and considering the effects of formation temperature,the orthotropic formation drillability anisotropy evaluation model is established;combining this model with the previous formation force model,the change of formation azimuth force under the influence of formation parameters(formation drillability anisotropy,formation geometry,inclination angle,azimuth angle,weight on bit)were calculated and analyzed;the main influence factors of azimuth drift and the method to control it were summarized for a field example.The optimization method of hole cleaning for long horizontal section well was put forward.I also wrote a software to predict the equivalence circulating density(ECD)and the horizontal section hydraulic length limit,which is verified by a field example,results show that the prediction error of ECD is less than 5%.This part of the research is of great significance for the safe drilling of long horizontal section wells.