The preparation and recycling of slurry is a very complicated and crucial task in large Horizontal Directional Drilling (HDD) river-crossing project. This paper introduced the successful and advanced experiences of the utilization and management of slurry in large HDD projects in China. Different property requirements of slurry in different periods of the project are discussed. Research is focused on the recycling system of slurry, including the filtration of slurry which returned from the drill hole, and how to add bentonite and additives in this filtrated slurry. The recycling of slurry can save a large amount of bentonite and additives. The disposal methods of waste mud in the job site were discussed, and two methods were recommended to be adopted to dispose waste mud. One is mechanical methods, using centrifugal machine; the other is chemical method, using chemical material to solidify waste mud.

As the installation of oil and gas pipeline increases rapidly, more and more Horizontal Directional Drilling (HDD) machines are utilized in China. The main function of slips in a HDD rig is to loosen the screw of two drill rods which are screwed up in the drilling or reaming process. The more tightly the drill rods are screwed, the larger the force acting on the drill rod, which can cause notches on drill rod. However, if the force is not big enough, there would be insufficient friction force to loosen the screw. The damage modes of the drill rod surface caused by slips indicate that the interaction mechanism between integrated slips and the drill rod is elastic, while the sharp teeth of combined slips can embed into the surface of drill rod. This assumption is proven by two calculation examples. ABAQUS is used to simulate the interaction mechanism between slip and drill rod, and the result is approximately coincided with the calculated results. The friction coefficient between slips and drill rod are calculated and then compared to the experiential results. Finally, some advice is given to solve the problem.