海洋天然气水合物保温保压取样钻具研制

Development of Marine Gas-hydrate Pressure and Temperature Core Sampler

天然气水合物作为一种新型清洁能源,广泛地分布在海底地层中。为了摸清我国海域天然气水合物的分布及储量,前期必须进行大量的钻探取样工作。鉴于天然气水合物特殊的赋存环境及物化特性,为了在取样过程中避免天然气水合物的分解,需要采用保真取样器来获取岩样。为此,研发了一种海洋天然气水合物保温保压取样钻具。该钻具采用了“板阀—脱钩机构”解决当前保真取样过程中保压成功率较低的难题,以取样筒的反向冲击压紧板阀,实现保压管的底部密封,大大提高了板阀密封的可靠性,进而提高了保压成功率。通过结构设计、试制、室内压力测试及海上钻井试验验证,该型保温保压取样钻具的保压成功率为75%,岩心收获率为72.14%。

As a new type of clean energy,natural gas hydrate is widely distributed in seabed strata.In order to find out the distribution of natural gas hydrate in Chinese sea area and reserves,drilling sampling needs to be obtained in the early stage.Based on the special physical-chemical properties of gas hydrate,pressure and temperature core sampler is needed to avoid gas-hydrate decomposition in sampling.Therefore one type of marine gas-hydrate pressure and temperature core sampler is developed.In order to solve the problem of low success rate of pressure holding during the fidelity sampling process,this drill tool adopts the " plate valve-decoupling mechanism" to realize the bottom sealing of pressure-holding pipe by the reverse impact of the sampling barrel and then pressing the plate valve.This method greatly improves the reliability of plate valve sealing and increases the success rate of pressure holding.Through structural design,trial production,laboratory pressure test and offshore drilling test,the pressure-holding success rate of the temperature and pressure core sampler is 75%,and core recovery rate is 72.14%.