海洋天然气水合物开采的固相控制策略*

天然气水合物是一种潜在的洁净能源资源,我国南海有丰富的储量,被认为是后石油时代的重要战略资源之一,然而目前大部分的海洋天然气水合物开采都受到出砂影响。针对深水天然气水合物开采过程中易出砂的现象,通过前期的出砂实验、理论和数值模拟,提出了海洋天然气水合物开采过程中固相（砂和水合物）控制方案。总结了天然气水合物开采过程中出砂特性和防砂案例,提出大颗粒水合物对泥质粉砂具有挡砂作用,进而影响防砂设计精度。据此,根据开发角度的天然气水合物藏6类细分,提出了考虑水合物颗粒本身及其分解作用的固相控制方法。结合南海天然气水合物储层公开资料,设计出相应的固相控制精度,以期最终形成出砂/防砂/井筒携砂/水合物二次生成预防为一体的固相控制体系,为南海天然气水合物安全高效地商业开发提供参考。

Solid Phase Control Strategy during the Exploitation of Marine Gas Hydrates

Natural gas hydrate is a potential clean energy resource. There are abundant reserves in the South China Sea, which is considered to be one of the significant strategic resources in the post-oil era. However, most of the marine gas hydrate exploitation is affected by sand production. In view of the phenomenon that sand is easy to be produced during the exploitation process of deep-water natural gas hydrate, based on the previous sand production experiment, theory and numerical simulation, a solid phase (sand and hydrate) control scheme during the process of marine natural gas hydrate exploitation was proposed. The sand production characteristics and sand control cases during the process of natural gas hydrate exploitation were summarized, and it was proposed that large particle hydrate had a sand-retaining effect on silty clay, which had affected the design accuracy of sand control. Accordingly, combined with the 6-subdivision classifications of natural gas hydrate reservoirs from the perspective of development, a solid phase control method considering the hydrate particles themselves and their decomposition was proposed. From the public information of natural gas hydrate reservoirs in the South China Sea, the corresponding solid phase control accuracy was designed, so as to finally form a solid phase control system integrating sand production/sand control/wellbore sand carrying/hydrate secondary formation prevention. This work may provide some references for the safe and efficient commercial development of natural gas hydrate in the South China Sea.