神狐海域水合物藏降压开采的数值模拟

目前在降压法开采水合物藏方面,主要侧重于对降压生产规律、水合物藏地质参数敏感性、降压法开采有效性及开发潜力等的研究,实际上在降压开采过程中,开采参数也会影响水合物藏的开采动态。根据神狐海域水合物藏现场资料,应用数值模拟的方法,进行了神狐海域2017年水合物试采试验的拟合,验证了所建地质模型的可靠性,在此基础上创新性地研究了降压幅度和降压速度对水合物藏开采动态的影响。研究结果表明:水合物未完全分解前,降压幅度越大,水合物分解速度越快,同一时刻产气速度也越快;降压速度越快,产气峰值越大且越早出现,同一时刻累产气越多。因此建议开采神狐水合物藏时降压幅度至少应为初始压力的0.5倍,并考虑实际操作工艺和设备安全性,选择较快的降压速度。

Numerical Study of Hydrate Depressurization Dissociation in Shenhu Area

At present, researches on hydrate depressurization mainly focuses on hydrate production rules, geological parameters sensitivity of hydrate reservoirs, efficiency and development potential. But in actual process of depressurization, development parameters have significantly effect on hydrate dynamic rules. Based on the basic data of the hydrate reservoir obtained from Shenhu area, the reliability of geological model has been verified by numerical study on hydrate pre-production test in 2017. The effect of development parameters (i.e. the depressurization amplitude and the depressurization rate) on hydrate development have been creatively studied. The simulation results show that: before the hydrate completely dissociates, with the increase of depressurization amplitude, at the same time, the hydrate within the reservoir dissociates faster and the gas production rate is larger. Besides, the faster depressurization rate leads to an earlier and larger peak in gas rate and the larger cumulative gas production. Accordingly, the depressurization amplitude at least half of the initial reservoir pressure is recommended, and a faster depressurization rate should be chose according to the practical operation and the safety of equipment for hydrate production in Shenhu area.