LABORATORY STUDY ON DRILLING HIGH MOLECULAR WEIGHT ADDITIVE JETTING

Based on the feature of radially horizontal drilling and the need of drilling through rock breaking hydraulic jetting,a labotatory study was conducted on effect of polyacrylamide(with MW greater than 1000×104) upon rock breaking. Test was done on an atmospheric tester with power provided a XY type triplex plunger pump. A synthetic core with ratio of cement to sand as 1: 1. 5 was used. For comparison,all the polyacrylamide slutions were used only once. The result showed that the addition of this HMW additive with proper concentration facilities rock breaking jetting;particularly its improvement to rock breaking rotory jetting with small jet length is remarkable;it can increase the optimum jet length in rock breaking circular jetting and the rock breaking effect of rototy jet added with the polymer is better than that of circular jet. Rock breaking result indicated that an optimum addition exists for jet added with HMW polymer.