Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzin...Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzing the driving forces, fluid pressure regimes, fluid flow rate and direction, and their relationships with localization of mineralization. This paper reviews the principles and methods of hydrodynamic studies of mineralization, and discusses their significance and limitations for ore deposit studies and mineral exploration. The driving forces of fluid flow may be related to fluid overpressure, topographic relief, tectonic deformation, and fluid density change due to heating or salinity variation, depending on specific geologic environments and mineralization processes. The study methods may be classified into three types, megascopic （field） observations, microscopic analyses, and numerical modeling. Megascopic features indicative of significantly overpressured （especially lithostatic or supralithostatic） fluid systems include horizontal veins, sand injection dikes, and hydraulic breccias. Microscopic studies, especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes （FIPs） can provide important information about fluid temperature, pressure, and fluid-structural relationships, thus constraining fluid flow models. Numerical modeling can be carried out to solve partial differential equations governing fluid flow, heat transfer, rock deformation and chemical reactions, in order to simulate the distribution of fluid pressure, temperature, fluid flow rate and direction, and mineral precipitation or dissolution in 2D or 3D space and through time. The results of hydrodynamic studies of mineralization can enhance our understanding of the formation nrocesses of hvdrothermal denosits, and can be used directly or indirectly in mineral exnloration.展开更多
Raising the in situ decomposition rate of natural gas hydrate and increasing the decomposition contact area are two main ways to raise the productivity of hydrate. An exploitation technique based on large borehole wit...Raising the in situ decomposition rate of natural gas hydrate and increasing the decomposition contact area are two main ways to raise the productivity of hydrate. An exploitation technique based on large borehole with multi-lateral branches (LB & MB) was proposed in this paper. This technique is mainly intended for the clayey silt hydrate reservoir in the South China Sea, and its main purpose is to alleviate the sand output from formation for maintaining the stability of the reservoir and to greatly increase the gas productivity of the reservoir. In this paper, the following aspects were mainly expounded: definition of the basic geometric parameters for layout of multi-lateral branches in clayey silt hydrate reservoir, simulation of the stimulation effect of a typical well profile with two branches, and prediction and simulation of the reservoir failure risk in a well profile with eight branches. The results show that the LB & MB effectively improves the flow field in the formation, raises the productivity of the reservoir and may also help to decrease the produced water-gas ratio (WGR). When the lateral branches spacing is too small, the failure zones around adjacent lateral branches overlap each other, possibly causing reservoir failure in a larger range. Therefore, the geometric parameters of multi-lateral branches depend on the dual control of the productivity and geotechnical risk factor of reservoir. Further study is being carried out, so as to obtain the optimal combination of parameters of multi-lateral branches.展开更多
基金supported by an NSERC-Discovery grant to Chi.Additional supports came from NSFC(41072069, 40772061 and 40930423)State Basic Research Plan (2009CB421005)+1 种基金IRT(0755) 111 Plan(B07011)
文摘Fluid flow is an integral part of hydrothermal mineralization, and its analysis and characterization constitute an important part of a mineralization model. The hydrodynamic study of mineralization deals with analyzing the driving forces, fluid pressure regimes, fluid flow rate and direction, and their relationships with localization of mineralization. This paper reviews the principles and methods of hydrodynamic studies of mineralization, and discusses their significance and limitations for ore deposit studies and mineral exploration. The driving forces of fluid flow may be related to fluid overpressure, topographic relief, tectonic deformation, and fluid density change due to heating or salinity variation, depending on specific geologic environments and mineralization processes. The study methods may be classified into three types, megascopic （field） observations, microscopic analyses, and numerical modeling. Megascopic features indicative of significantly overpressured （especially lithostatic or supralithostatic） fluid systems include horizontal veins, sand injection dikes, and hydraulic breccias. Microscopic studies, especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes （FIPs） can provide important information about fluid temperature, pressure, and fluid-structural relationships, thus constraining fluid flow models. Numerical modeling can be carried out to solve partial differential equations governing fluid flow, heat transfer, rock deformation and chemical reactions, in order to simulate the distribution of fluid pressure, temperature, fluid flow rate and direction, and mineral precipitation or dissolution in 2D or 3D space and through time. The results of hydrodynamic studies of mineralization can enhance our understanding of the formation nrocesses of hvdrothermal denosits, and can be used directly or indirectly in mineral exnloration.
基金This research was supported by Project of Distinguished Experts of Taishan Scholars (ts201712079)Youth Foundation of National Natural Science Foundation of China (41606078)+1 种基金Open Foundation of Pilot National Laboratory for Marine Science and Technology (QNLM2016ORP0207)Marine Geological Survey Program (DD20190231). Anonymous reviewers and Dr. Hao Zi-guo and Dr. Yang Yan were grateful for their constructive suggestions on the manuscript.
文摘Raising the in situ decomposition rate of natural gas hydrate and increasing the decomposition contact area are two main ways to raise the productivity of hydrate. An exploitation technique based on large borehole with multi-lateral branches (LB & MB) was proposed in this paper. This technique is mainly intended for the clayey silt hydrate reservoir in the South China Sea, and its main purpose is to alleviate the sand output from formation for maintaining the stability of the reservoir and to greatly increase the gas productivity of the reservoir. In this paper, the following aspects were mainly expounded: definition of the basic geometric parameters for layout of multi-lateral branches in clayey silt hydrate reservoir, simulation of the stimulation effect of a typical well profile with two branches, and prediction and simulation of the reservoir failure risk in a well profile with eight branches. The results show that the LB & MB effectively improves the flow field in the formation, raises the productivity of the reservoir and may also help to decrease the produced water-gas ratio (WGR). When the lateral branches spacing is too small, the failure zones around adjacent lateral branches overlap each other, possibly causing reservoir failure in a larger range. Therefore, the geometric parameters of multi-lateral branches depend on the dual control of the productivity and geotechnical risk factor of reservoir. Further study is being carried out, so as to obtain the optimal combination of parameters of multi-lateral branches.
