Horizontal Well Bending Shell Screw Drilling Set Combination Forecasting

Horizontal well has become the main way of exploitation of crude oil and natural gas reservoir because of low cost. Well trajectory is always the vital of horizontal drilling, which is able to decide the target of drilling. RSS, which could outstandingly adjust well path, was firstly used in the horizontal drilling by an American corporation. Nevertheless, the cost of RSS is still too high to be used in the process of drilling in China. The main deflection tool in China, therefore, is certainly bent PDM (positive displacement mud motor).Nowadays, sliding drilling and compound drilling are performed in horizontal well. Well trajectory caused by compound drilling shows different tendency. National Science and Technology Major Project set up a branch (Contract Number:2011ZX05021-006) about analyzing force of BHA and predicting tendency of trajectory performed by the bent PDM.This paper elected the beam-column method and the statistics to build models for predicting the tendency of trajectory after researching widely the methods. The key elements were chosen by analyzing force of bent PDM in different performance. Finally, prediction models were set up with those essential factors via statistics.WOB and inclination angle are conspicuous elements affecting the tendency of trajectory in sliding drilling, which were proved by analyzing the force of PDM with a bent housing. On the other hand, mechanics analysis proved that WOB, inclination, borehole curvature are significant components of predicting well trajectory in compound drilling. Model built for predicting the tendency of trajectory in sliding drilling regarded WOB, inclination angle, bit side force, bit tilt angle and force of layer as key elements. Other model for compound drilling was with five essential factors that are WOB, inclination, force on bit, borehole curvature and stratum.The prediction model for sliding drilling, which was built with data in YB area, shows influence of WOB, bit side force and force of layer. The other model for predicting well trajectory in compound drilling reflected WOB, force on bit and force of stratum. Prediction with the models shows high accordance with the performance in YB area, which was more than80%.The method, which uses the beam-column method and statistics to predict tendency of trajectory, has been truly proved by the research. The software about analyzing force on bent PDM and predicting tendency of trajectory, which developed through using the method, is able to predict the tendency and analyzing accurately bit side force. It could be used for choosing drilling tools and adjusting parameters. The software developed on the WPF platform is able to run on win7and other high grade systems. In order to using the method more effectively, the survey tools need to be upgraded as soon as possible.