Abstract: A perforating device includes a release sub, a rotating segment, a first centralizer, a braking segment, a casing collar locator, a traction mechanism, a second centralizer, a flex joint, a power supply segment, a shock absorber, a perforator, and a tail segment, which are in threaded connection sequentially to each other. The first joint assembly includes a first joint, a guide key, a connecting sleeve including a locking groove, a second joint, and an outer pipe; the first joint of the first joint assembly is in threaded connection to the cable bridle, and the second joint is in threaded connection to the outer pipe. The connecting sleeve is disposed inside the outer pipe and is connected to the first joint through the guide key. The second joint assembly includes a plurality of locking claws, a third joint, and a head.

Abstract: The present disclosure discloses a comb polymer or a salt thereof, wherein the structural formula of the comb polymer containing the following constitutional units. When the comb polymer provided in the present disclosure is used in a water-based drilling fluid as a filtration control agent, it can eliminate the defects of conventional filtration control agents which would be subject to ineffectiveness under high temperature and high salinity conditions. The comb polymer has high temperature and salt resistance, and can be produced through simple processes at comparatively low costs. When the comb polymer provided by the present disclosure is used as a filtration control agent, even being added into the drilling fluid at a comparatively low amount, it can still present rather good effects in lowering the amount of filter loss.