Hair clip type core lifter for improving coring quality in complex formation and its ap-plication

In order to solve the coring problem of the coring tools during drilling weak loose and complex formation, to decrease the probability of the blocking and wearing core, to increase the footage per round trip and the coring rate, a new type coring lifter installed in the common S95 wire coring drilling tool has been developed. The coring lifter uses the female hair clip to collect the weak loose core. The hair clip core lifter is composed of a hair clip, a hair clip seat and a hair clip room, doesn't need to be fixed trough rivet welding technology, can be assemble manually in the working site with the help of a hair clip assembler. It has been tested in three boreholes in a coal mine. The total footage of the tested interval was 45.11 m, the average footage per round trip was 1.16 m, the average coring rate was 91.42%. The test results show that when combined with the bottom jet bit and the core-guiding barrel the hair clip core lifter can increase greatly the footage per round trip, improve the coring rate and quality, solve the difficult problem that before the test with the common wire coring drilling tool, the coring rate of the soft intercalated stones and strongly water-sensitive complex formation was less than 30%. Compared with the current similar technology of clipping core with plate spring, the method of using the hair clip to collect the weak and loose core is more economical, more flexible and more adoptable. Its application field is not only not limited in mine ge-ology, but also can be expanded to the coring drilling in hydrogeology, engineering geology, environmental geology, it has a wide application prospect.