Design Of Polyurethane Borehole Injector Applied To Wire-line Core Drilling

Now,wire-line core drilling technology is generally used in core drilling,because of its outstanding advantages of getting core without pulling and setting drill bit,which reducing the labor intensity greatly and saving working time,in addition,ithas advantages such as high quality borehole and low cost.When drilling complicated formations, however, it is inevitable to appear the phenomenon of drilling leakage, which severely inhibits drilling efficiency and likely causes safety problem. It is essential to research the problem of drilling leakage when it comes to avoid drilling accident. In order to achieve the goal of high-efficiency drilling without safety problem, it is therefore necessary to develop a novel method to seal drilling leakage.Through comparing different wall plugging technologies, it is concluded that a rapid wall plugging technology turns out to be both efficient and economical. During this process, a borehole irrigator becomes an essential mechanism to transfer the sealing agent(polyurethane) into the target broken formation. The borehole irrigator is generally linked directly with drill bit, which leads to a low drilling efficiency due to repeated round tripping operations. A novel borehole irrigator was already developed without tripping operation.The non-toxic polyurethane has excellent properties of elasticity and strength. It has two basic types according to the number of its components:single and double. Due to higher cost of the polyurethane consisting of double components, the polyurethane with single component is the most widely used in practice. In order to simplify its structure, a borehole irrigator with single chamber was developed.The borehole injector is controlled by hydraulic piston. Two check valves are installed on both ends of the injector to enhance the sealing effect. In order to avoid the fluid flowing back into drill tool, a U cup is installed at the position near drill bit, under which, in addition, is installed a packer to avoid the fluid return back the gap between drill tool and borehole wall. This packer works through the pressure difference to drive the removable parts upwards to seal the gap between the drill tool and borehole wall.All parts have been theoretically checked and selected according to national standards. An overall processing map was eventually pictured based on previous design.