海域天然气水合物保压取心钻具的研制与试验

Development and experiment of pressure core sampler for marine natural gas hydrates

摘要:

天然气水合物的勘探和开发需要从地层中获取保压岩心进行地层的物化性测试、储量评估以及开采工艺等方面的研究。然而，钻探过程中，伴随温度和压力的改变，天然气水合物很容易发生分解，这给水合物钻探取心工作带来了很大的困难。为了解决天然气水合物保压取心钻具的保压可靠性问题，开展了一种新型齿轮-齿条关闭球阀式水合物保压取心钻具的研制，采用绳索打捞的提拉力驱动球阀工作。详细介绍了该保压取心钻具的结构和工作原理；计算了球阀的工作密封比压及打捞内管所需的提拉力；介绍了该保压取心钻具的室内试验和海试情况。研究表明：该水合物保压取心钻具的取心工艺简单、球阀翻转和密封性能良好、取心成功率高，各项功能和性能指标均达到了设计的要求。

Abstract:

The exploration and exploitation of natural gas hydrate need to obtain the pressurized core from the formation for physicochemical property testing， reserve evaluation and mining technology research. However， in the process of drilling， gas hydrate is easily decomposed with the change of temperature and pressure， which brings great difficulties to the core drilling of hydrate. In order to solve the pressure maintaining reliability problem of gas hydrate pressure maintaining coring drill， the project team developed a new type of gear and rack closed ball valve for gas hydrate pressure maintaining coring drill. The ball valve was driven by lifting force of rope fishing. The structure and working principle of the pressure maintaining core drill are introduced in detail. The specific pressure of working seal of ball valve and lifting force required for fishing inner pipe are calculated. The indoor test and sea test of the pressure maintaining core drill are introduced. The research shows that the hydrate pressure retaining coring drill has the advantages of simple coring process， good reversing and sealing performance of ball valve， high success rate of coring， and all functions and performance indexes meet the design requirements.