摘要:
天然气水合物一般赋存在深海海底浅层地层中，受扰动易分解，采用常规取心工具难以取得样品，为此进行了天然气水合物保温保压取心工具的研制与现场试验。采用三维设计软件设计了绳索式天然气水合物保温保压取心工具整体结构，介绍了伸缩插入式、活塞射入式、冲击器冲击式和马达旋转式4种类型取心工具的具体结构和工作原理；为使研制的取心工具具有保持温度和压力、压力补偿、快速打捞和减小取心扰动等功能，研究了保温保压取心关键技术。通过室内模拟分析保压密封阀、保温筒、压力补偿装置、岩心管、绳索打捞回收装置等关键部件，证明保压密封阀可保压30.0 MPa，保温筒采取填充隔热复合材料二氧化硅气凝胶的方式，受环境温度的影响减小，其他部件的性能也都符合设计要求。南海LW3区块天然气水合物赋存区2口井13回次的取样试验结果表明，研制的绳索式天然气水合物保温保压取心工具能够成功取心，为国内天然气水合物的自主勘探取心提供了技术支撑。
Abstract:
Natural gas hydrates that exist in the shallow strata of deep sea floor are notoriously unstable and are easily decomposed when disturbed.It is difficult to obtain samples by conventional coring technology.Therefore,the development and field test of pressure-temperature preservation coring tools for gas hydrate have been carried out.3D software was used to design the overall structure of rope-type pressure-temperature preservation coring tools for gas hydrate.The test incorporated the detailed structures and working principles of four types of coring tools,including telescopic insertion type,piston injection type,impact type and motor rotation type.In order to assure that the tools can maintain constant temperature and pressure,and that they also will have the attributes of pressure compensation,rapid fishing,and reduced coring disturbance,we studied the key technologies of pressure-temperature preservation coring tools.We conducted indoor simulation analysis on key parts such as pressure sealing valve,heat insulation tube,pressure compensation device,core tube,and rope fishing and recovery device.The results showed that the pressure sealing valve could withstand pressure 30.0 MPa,they also demonstrated that an insulation barrel filled with heat insulation composite silica aerogel could reduce the influence of ambient temperature on it,and the performances of other components also meet the design requirements.We completed 13 runs of sampling in two wells in the gas hydrate reservoir of LW3 Block in the South China Sea.Our results demonstrate that the rope-type pressure-temperature preservation coring tools can successfully take gas hydrate cores.This new understanding and knowledge will provide technical support for the independent exploration and coring of gas hydrates in China in the future.
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