The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been bu...The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been built in China since the 1970s, there is still a lack of experience for large-volume underground storage in complicated geological conditions. The current design concept of water curtain system and the technical instruction for system operation have limitations in maintaining the stability of surrounding rock mass during the construction of the main storage caverns, as well as the long-term stability. Although several large-scale underground oil storage projects are under construction at present in China, the design concepts and construction methods, especially for the water curtain system, are mainly based on the ideal porosity medium flow theory and the experiences gained from the similar projects overseas. The storage projects currently constructed in China have the specific features such as huge scale, large depth, multiple-level arrangement, high seepage pressure, complicated geological conditions, and high in situ stresses, which are the challenging issues for the stability of the storage caverns. Based on years’ experiences obtained from the first large-scale （millions of cubic meters） underground water-sealed oil storage project in China, some design and operation problems related to water curtain system during project construction are discussed. The drawbacks and merits of the water curtain system are also presented. As an example, the conventional concept of “filling joints with water” is widely used in many cases, as a basic concept for the design of the water curtain system, but it is immature. In this paper, the advantages and disadvantages of the conventional concept are pointed out, with respect to the long-term stability as well as the safety of construction of storage caverns. Finally, new concepts and principles for design and construction of the underground water-sealed oil storage caverns are proposed.展开更多
Oil and gas can be stored underground by a variety of means,such as in depleted oil and gas fields,in aquifers,in rock salt caverns,in unlined mined rock caverns,in lined shallow caverns and abandoned mines.Different ...Oil and gas can be stored underground by a variety of means,such as in depleted oil and gas fields,in aquifers,in rock salt caverns,in unlined mined rock caverns,in lined shallow caverns and abandoned mines.Different types of underground storages require different geological and hydrogeological conditions and are associated with different rock engineering problems.However,the common issue is to ensure the gas-and oil-tightness of storage caverns.In other words,the stored oil and gas must not escape from the storage caverns.This may be realized by different means according to the types of storages and the sites geological conditions.There are basically two approaches of gas leakage control,i.e.permeability control and hydrodynamic containment.The latter involves the use of a water curtain system in many cases,which creates an artificial hydraulic boundary condition and helps to establish the required groundwater condition when needed.In addition to the common problems,the underground storage of liquefied petroleum gas(LPG) requires special attentions to the opening of rock joints,which result from the tensile thermal stress induced by the low storage temperature.Great care must be taken in choosing abandoned mines for oil and gas-storage since it is quite rare that the natural site conditions can meet the usual requirements,in particular for the gas tightness.The paper provides a general description of the gas leakage control for underground oil and gas storage projects,and addresses various rock engineering problems associated with selected types of storages in detail.展开更多
Water curtain systems(WCSs)are key components for the operation of underground oil storage caverns(UOSCs)and their optimization and design are important areas of research.Based on the time series monitoring of the fir...Water curtain systems(WCSs)are key components for the operation of underground oil storage caverns(UOSCs)and their optimization and design are important areas of research.Based on the time series monitoring of the first large-scale underground water-sealed storage cavern project in China,and on finite element analysis,this study explores the optimum design criteria for WCSs in water-sealed oil caverns.It shows that the optimal hole spacing of the WCS for this underground storage cavern is 10 m in order to ensure seal effectiveness.When the WCS is designed with a 10-m horizontal hole spacing and a water curtain pressure(WCP)of 80 kPa,a water curtain hole(WCH)has an influence radius of approximately 25 m.The smaller the vertical distance is between a WCH and the main cavern,the greater the water inflow into the main cavern.The vertical hydraulic gradient criterion can be satisfied when this distance is 25 m.It shows that the optimal WCP is 70 kPa,which meets sealing requirements.展开更多
Since the beginning of this century, revolutionary progress has been made in the understanding of resources and in the mining technologies of the oil and gas industry. Advances in petroleum engineering technology repr...Since the beginning of this century, revolutionary progress has been made in the understanding of resources and in the mining technologies of the oil and gas industry. Advances in petroleum engineering technology represented by horizontal wells and large-scale fracturing have promoted the scale development of low-grade and unconventional oil and gas resources. After the rapid growth of natural gas production in China for more than 10 consecutive years, the replacement of conventional natural gas resources has been weak and unconventional natural gas has become the major force for increasing production. Coal based SNG(synthetic natural gas) has also become a major competitor in the domestic market. The development of CTL(coal-toliquids) and SNG industries has brought coal resources into the oil and gas product market, expanding the concept of traditional oil and gas resources. The continuous improvement of petroleum engineering technology has promoted the development of deep underground coal gasification technology, which has given economic value to the huge amount of deep coal resources that are unable to be exploited by underground mining, and provides a tremendous resource guarantee for the sustainable development of the traditional oil and gas industry. A preliminary calculation shows that deep underground coal gasification has a competitive advantage in cost compared with high-cost, low-grade, unconventional gas and coal-based natural gas. Deep underground coal gasification is a typical cross-disciplinary and cross-sectoral sophisticated technology. Domestic oil and gas enterprises have dominant advantages in the engineering technology of this field. Further technical integration innovation and multi-industry joint research are needed to eventually realize the commercial application of this deep underground coal gasification technology.展开更多
文摘The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been built in China since the 1970s, there is still a lack of experience for large-volume underground storage in complicated geological conditions. The current design concept of water curtain system and the technical instruction for system operation have limitations in maintaining the stability of surrounding rock mass during the construction of the main storage caverns, as well as the long-term stability. Although several large-scale underground oil storage projects are under construction at present in China, the design concepts and construction methods, especially for the water curtain system, are mainly based on the ideal porosity medium flow theory and the experiences gained from the similar projects overseas. The storage projects currently constructed in China have the specific features such as huge scale, large depth, multiple-level arrangement, high seepage pressure, complicated geological conditions, and high in situ stresses, which are the challenging issues for the stability of the storage caverns. Based on years’ experiences obtained from the first large-scale （millions of cubic meters） underground water-sealed oil storage project in China, some design and operation problems related to water curtain system during project construction are discussed. The drawbacks and merits of the water curtain system are also presented. As an example, the conventional concept of “filling joints with water” is widely used in many cases, as a basic concept for the design of the water curtain system, but it is immature. In this paper, the advantages and disadvantages of the conventional concept are pointed out, with respect to the long-term stability as well as the safety of construction of storage caverns. Finally, new concepts and principles for design and construction of the underground water-sealed oil storage caverns are proposed.
文摘Oil and gas can be stored underground by a variety of means,such as in depleted oil and gas fields,in aquifers,in rock salt caverns,in unlined mined rock caverns,in lined shallow caverns and abandoned mines.Different types of underground storages require different geological and hydrogeological conditions and are associated with different rock engineering problems.However,the common issue is to ensure the gas-and oil-tightness of storage caverns.In other words,the stored oil and gas must not escape from the storage caverns.This may be realized by different means according to the types of storages and the sites geological conditions.There are basically two approaches of gas leakage control,i.e.permeability control and hydrodynamic containment.The latter involves the use of a water curtain system in many cases,which creates an artificial hydraulic boundary condition and helps to establish the required groundwater condition when needed.In addition to the common problems,the underground storage of liquefied petroleum gas(LPG) requires special attentions to the opening of rock joints,which result from the tensile thermal stress induced by the low storage temperature.Great care must be taken in choosing abandoned mines for oil and gas-storage since it is quite rare that the natural site conditions can meet the usual requirements,in particular for the gas tightness.The paper provides a general description of the gas leakage control for underground oil and gas storage projects,and addresses various rock engineering problems associated with selected types of storages in detail.
基金Project supported by the National Natural Science Foundation of China (Nos. 41877239, 51379112, 51422904, 40902084, and 41772298)the Fundamental Research Funds for the Central Universities (No. 2018JC044)the Natural Science Foundation of Shandong Province (No. JQ201513),China。
文摘Water curtain systems(WCSs)are key components for the operation of underground oil storage caverns(UOSCs)and their optimization and design are important areas of research.Based on the time series monitoring of the first large-scale underground water-sealed storage cavern project in China,and on finite element analysis,this study explores the optimum design criteria for WCSs in water-sealed oil caverns.It shows that the optimal hole spacing of the WCS for this underground storage cavern is 10 m in order to ensure seal effectiveness.When the WCS is designed with a 10-m horizontal hole spacing and a water curtain pressure(WCP)of 80 kPa,a water curtain hole(WCH)has an influence radius of approximately 25 m.The smaller the vertical distance is between a WCH and the main cavern,the greater the water inflow into the main cavern.The vertical hydraulic gradient criterion can be satisfied when this distance is 25 m.It shows that the optimal WCP is 70 kPa,which meets sealing requirements.
文摘Since the beginning of this century, revolutionary progress has been made in the understanding of resources and in the mining technologies of the oil and gas industry. Advances in petroleum engineering technology represented by horizontal wells and large-scale fracturing have promoted the scale development of low-grade and unconventional oil and gas resources. After the rapid growth of natural gas production in China for more than 10 consecutive years, the replacement of conventional natural gas resources has been weak and unconventional natural gas has become the major force for increasing production. Coal based SNG(synthetic natural gas) has also become a major competitor in the domestic market. The development of CTL(coal-toliquids) and SNG industries has brought coal resources into the oil and gas product market, expanding the concept of traditional oil and gas resources. The continuous improvement of petroleum engineering technology has promoted the development of deep underground coal gasification technology, which has given economic value to the huge amount of deep coal resources that are unable to be exploited by underground mining, and provides a tremendous resource guarantee for the sustainable development of the traditional oil and gas industry. A preliminary calculation shows that deep underground coal gasification has a competitive advantage in cost compared with high-cost, low-grade, unconventional gas and coal-based natural gas. Deep underground coal gasification is a typical cross-disciplinary and cross-sectoral sophisticated technology. Domestic oil and gas enterprises have dominant advantages in the engineering technology of this field. Further technical integration innovation and multi-industry joint research are needed to eventually realize the commercial application of this deep underground coal gasification technology.
