Normal-pressure shale gas is an important object of shale gas reserves and production increasewith broad resource prospects in China,but its large-scale benefit development is still confronted with technical bottlenec...Normal-pressure shale gas is an important object of shale gas reserves and production increasewith broad resource prospects in China,but its large-scale benefit development is still confronted with technical bottlenecks.To promote the large-scale benefit development of normal-pressure shale gas,this paper systematically sorts out and summarizes the research achievements and technological progresses related to normal-pressure shale gas from the aspects of accumulation mechanism,enrichment theory,percolation mechanism,development technology,and low-cost engineering technology,and points out the difficulties and challenges to the benefit development of normal-pressure shale gas in the complex structure zones of southern China,by taking the shale gas in the Southeast Chongqing Area of the Sichuan Basin as the research object.In addition,the research direction of normal-pressure shale gas exploration and development is discussed in terms of sweet spot selection,development technology policy,low-cost drilling technology and high-efficiency fracturing technology.And the following research results are obtained.First,the accumulation mechanism of normal-pressure shale gas is clarified from the perspective of geological exploration theory;the hydrocarbon accumulation model of generation,expulsion,retention and accumulation is established;the enrichment theory of“three-factor controlling reservoir”is put forward;and the comprehensive sweetspot target evaluation system is formed.Second,as for development technology,the development technology policies of“multiple series of strata,variable well spacing,long horizontal section,small included angle,low elevation difference,strong stimulation and pressure difference controlling”are formulated.Third,as for drilling engineering,the optimal fast drilling and completion technology with“secondary structureþradical parameterþintegrated guidanceþunpressured leak-proof cementing”as the core is formed.Fourth,as for fracturing engineering,the low-cost and high-efficiency fracturing technology with“multi-cluster small-stageþlimited-entry perforatingþdouble temporary blockingþhigh-intensity sand injectionþfully electric”as the core is formed.Fifth,normal-pressure shale gas is characterized by complex geological conditions,low pressure coefficient and gas content,poor resource endowment and so on,but its resource utilization still faces a series of challenges,such as uncertain productivity construction positions,low single-well productivity and ultimate recoverable reserve,high investment cost and poor economic benefit.In conclusion,the key research directions to realize the large-scale benefit development of low-grade normal-pressure shale gas are to deepen the research on the enrichment and high yield mechanism and sweet spot selection of normal-pressure shale gas,strengthen the research on the benefit development technology policy based on percolation mechanism and the key technologies for low-cost drilling,accelerate the research and devel-opment of the key technologies for low-cost and high-efficiency fracturing,and implement cost reduction and efficiency improvement continuously.展开更多
Through systematic investigation of deep coal-rock gas in the Ordos Basin,NW China,this work analysed the thickness distribution of the entire Upper Paleozoic coal-rock intervals,quantified the resource potential of r...Through systematic investigation of deep coal-rock gas in the Ordos Basin,NW China,this work analysed the thickness distribution of the entire Upper Paleozoic coal-rock intervals,quantified the resource potential of representative areas(a 12000 km2 rectangular block in the eastern Ordos Basin roughly centered on Yulin City),clarified the occurrence characteristics of coal-rock gas,and identified key development indicators for gas wells,thereby defining the direction for iterative optimization of key technologies.(1)The total coal-rock gas in-place of the Upper Paleozoic coal seams 1^(#)-10^(#)in the resource evaluation region is assessed at 5.66×10^(12) m^(3),of which coal seam 8^(#),currently the main target interval,contains about 3.08×10^(12) m^(3),accounting for roughly 54%of the total.(2)Deep coal-rock gas is characterized by a high ratio of free gas.Under the conditions of 2000 m burial depth,6.35%porosity,95%free gas saturation,and 22.13 m^(3)/t total gas content,the free gas content of the reservoir is estimated to be ca.40%of the total gas.(3)Three productivity evaluation models(triangular,convex,concave)are developed for horizontal wells,of which the triangular model can serve as the reference model for predicting the estimated ultimate recovery(EUR)throughout the lifecycle of coal-rock gas wells.Using the triangular model with a 7 m coal thickness,1500 m effective lateral length and 400 m well spacing,the average single-well EUR is determined to be 4621.28×10^(4) m^(3).(4)Development of the coal seam 8^(#)should employ horizontal wells with pressure-controlled production.Meanwhile,it can be further optimized by adopting the cost-effective strategies of Sulige Gas Field in the Ordos Basin,China.(5)To achieve cost-effective development and increase primary recovery factor,key technologies must undergo continuous iteration and upgrading,focusing on accelerating drilling,extending effective lateral lengths,high-intensity reservoir stimulation,and well-pattern optimization.展开更多
The strategic role of health care within the Brazilian development agenda has been increasingly recognized and institutionalized. Aside from its importance as a structural element of the Welfare State, health care pla...The strategic role of health care within the Brazilian development agenda has been increasingly recognized and institutionalized. Aside from its importance as a structural element of the Welfare State, health care plays a leading role in generating innovation. Despite this, the productive base of Brazil’s health care system is extremely fragile, jeopardizing both the universal provision of health care services and the country’s competitive insertion in the globalized environment. This suggests the need for a more systematic analysis of the complex relationships that exist between the technological and the social interests involved in the productive base of health care provision in Brazil. Therefore, the purpose of this article is to enhance our understanding of the productive base of health care, especially given its potential to contribute to a socially inclusive development model, which is the ultimate goal in Brazil.展开更多
基金supported by the National Science and Technology Major Project of China"Demonstrative project of normal-pressure shale gas exploration and development in the Pengshui area"(No.2016ZX05061)the Sinopec Scientific Research Projects"Evaluation of normal-pressure shale gas enrichment and production mechanisms and targets in Nan-chuan-Wulong"(No.P21087-6)"Evaluation of shale gas enrichment and targets in the East China exploration area in Sichuan Basin and its periphery"(No.P20059-6).
文摘Normal-pressure shale gas is an important object of shale gas reserves and production increasewith broad resource prospects in China,but its large-scale benefit development is still confronted with technical bottlenecks.To promote the large-scale benefit development of normal-pressure shale gas,this paper systematically sorts out and summarizes the research achievements and technological progresses related to normal-pressure shale gas from the aspects of accumulation mechanism,enrichment theory,percolation mechanism,development technology,and low-cost engineering technology,and points out the difficulties and challenges to the benefit development of normal-pressure shale gas in the complex structure zones of southern China,by taking the shale gas in the Southeast Chongqing Area of the Sichuan Basin as the research object.In addition,the research direction of normal-pressure shale gas exploration and development is discussed in terms of sweet spot selection,development technology policy,low-cost drilling technology and high-efficiency fracturing technology.And the following research results are obtained.First,the accumulation mechanism of normal-pressure shale gas is clarified from the perspective of geological exploration theory;the hydrocarbon accumulation model of generation,expulsion,retention and accumulation is established;the enrichment theory of“three-factor controlling reservoir”is put forward;and the comprehensive sweetspot target evaluation system is formed.Second,as for development technology,the development technology policies of“multiple series of strata,variable well spacing,long horizontal section,small included angle,low elevation difference,strong stimulation and pressure difference controlling”are formulated.Third,as for drilling engineering,the optimal fast drilling and completion technology with“secondary structureþradical parameterþintegrated guidanceþunpressured leak-proof cementing”as the core is formed.Fourth,as for fracturing engineering,the low-cost and high-efficiency fracturing technology with“multi-cluster small-stageþlimited-entry perforatingþdouble temporary blockingþhigh-intensity sand injectionþfully electric”as the core is formed.Fifth,normal-pressure shale gas is characterized by complex geological conditions,low pressure coefficient and gas content,poor resource endowment and so on,but its resource utilization still faces a series of challenges,such as uncertain productivity construction positions,low single-well productivity and ultimate recoverable reserve,high investment cost and poor economic benefit.In conclusion,the key research directions to realize the large-scale benefit development of low-grade normal-pressure shale gas are to deepen the research on the enrichment and high yield mechanism and sweet spot selection of normal-pressure shale gas,strengthen the research on the benefit development technology policy based on percolation mechanism and the key technologies for low-cost drilling,accelerate the research and devel-opment of the key technologies for low-cost and high-efficiency fracturing,and implement cost reduction and efficiency improvement continuously.
基金Supported by the Scientific Research and Technology Development Project of PetroChina Company Limited(2023YQX103)Scientific Research and Technology Development Project of China National Petroleum Corporation(2024DJ86).
文摘Through systematic investigation of deep coal-rock gas in the Ordos Basin,NW China,this work analysed the thickness distribution of the entire Upper Paleozoic coal-rock intervals,quantified the resource potential of representative areas(a 12000 km2 rectangular block in the eastern Ordos Basin roughly centered on Yulin City),clarified the occurrence characteristics of coal-rock gas,and identified key development indicators for gas wells,thereby defining the direction for iterative optimization of key technologies.(1)The total coal-rock gas in-place of the Upper Paleozoic coal seams 1^(#)-10^(#)in the resource evaluation region is assessed at 5.66×10^(12) m^(3),of which coal seam 8^(#),currently the main target interval,contains about 3.08×10^(12) m^(3),accounting for roughly 54%of the total.(2)Deep coal-rock gas is characterized by a high ratio of free gas.Under the conditions of 2000 m burial depth,6.35%porosity,95%free gas saturation,and 22.13 m^(3)/t total gas content,the free gas content of the reservoir is estimated to be ca.40%of the total gas.(3)Three productivity evaluation models(triangular,convex,concave)are developed for horizontal wells,of which the triangular model can serve as the reference model for predicting the estimated ultimate recovery(EUR)throughout the lifecycle of coal-rock gas wells.Using the triangular model with a 7 m coal thickness,1500 m effective lateral length and 400 m well spacing,the average single-well EUR is determined to be 4621.28×10^(4) m^(3).(4)Development of the coal seam 8^(#)should employ horizontal wells with pressure-controlled production.Meanwhile,it can be further optimized by adopting the cost-effective strategies of Sulige Gas Field in the Ordos Basin,China.(5)To achieve cost-effective development and increase primary recovery factor,key technologies must undergo continuous iteration and upgrading,focusing on accelerating drilling,extending effective lateral lengths,high-intensity reservoir stimulation,and well-pattern optimization.
文摘The strategic role of health care within the Brazilian development agenda has been increasingly recognized and institutionalized. Aside from its importance as a structural element of the Welfare State, health care plays a leading role in generating innovation. Despite this, the productive base of Brazil’s health care system is extremely fragile, jeopardizing both the universal provision of health care services and the country’s competitive insertion in the globalized environment. This suggests the need for a more systematic analysis of the complex relationships that exist between the technological and the social interests involved in the productive base of health care provision in Brazil. Therefore, the purpose of this article is to enhance our understanding of the productive base of health care, especially given its potential to contribute to a socially inclusive development model, which is the ultimate goal in Brazil.
