The large reef complexes of the Upper Permian Changxing Formation, with a significant breakthrough for petroleum exploration, are an important target for petroleum exploration in the Yuanba area of the Sichuan Basin i...The large reef complexes of the Upper Permian Changxing Formation, with a significant breakthrough for petroleum exploration, are an important target for petroleum exploration in the Yuanba area of the Sichuan Basin in SW China. The storage space types of reef complexes are dominated by the dissolved pore-fracture（DPF）. However, using only single geophysical methods, it is difficult to predict effective distribution of DPF. Based on a combination of geological models and geophysics technology, this study proposes two new geophysical methods, including anisotropy coherence technique（ACT） and fracture intensity inversion（FII）, to research the characteristics of DPF by faciescontrolling in Changxing Formation in Yuanba area. Two major findings are presented as follows：（1） the characteristics of DPF varying with facies are the result of different diagenetic and petrophysical property. The intensity of DPF decreases from reef and bioclastic bank to interbank sea and slope;（2） ACT can qualitatively identify the distribution of DPF with no-directional and dispersed distribution, while FII can quantitatively characterize the intensity of DPF development within various sedimentary facies. When integrated into the geological study, ACT and FII can provide an effective way to predict the distribution of DPF in similar geological settings and the predicted DPF have been supported by the historical well data.展开更多
Very thick, fine-grained quartzose sandstone of the Lower Carboniferous (called the Donghe sandstone) was discovered in Donghe-1 well in the Tarim basin. Highly-productive commercial oil and gas flows were obtained wh...Very thick, fine-grained quartzose sandstone of the Lower Carboniferous (called the Donghe sandstone) was discovered in Donghe-1 well in the Tarim basin. Highly-productive commercial oil and gas flows were obtained when a well completion test was conducted. This important discovery proved that the quartzose sandstone is a prospecting target with good prospects. After that, other two paying oil and gas flows were found in the Lower Carboniferous in the Tazhong-4 and Tazhong-10 structures (Tazhong means central Tarim), equivalent to the Donghe sandstone. The Tazhong-4 structural oil field is the biggest oil field ever discovered. Therefore it is of guiding importance in oil and gas exploration to deepen the study of sedimentary and reservoir features and the sedimentary environment of the Donghe sandstone and to build a sedimentary model in order to understand the reservoir distribution pattern.展开更多
The positive structure belts surrounding the Taibei Sag,Turpan-Hami Basin,have been the main targets for oil and gas exploration for years and are now left with remaining resources scattering in reservoirs adjacent to...The positive structure belts surrounding the Taibei Sag,Turpan-Hami Basin,have been the main targets for oil and gas exploration for years and are now left with remaining resources scattering in reservoirs adjacent to source rocks in the sag,where the Shuixigou Group with substantial oil and gas potential constitutes the primary focus for near-source exploration.Consequently,characterization of development and key controlling factors of reservoir space becomes a must for future exploration in the area.This study investigates the development traits,genesis,and controlling factors of the Xishanyao and Sangonghe formations in the Shengbei and Qiudong Sub-sags of the Taibei Sag with techniques such as cast thin-section observation,porosity and permeability tests,high-pressure mercury injection,and saturation fluid NMR analysis of reservoir rocks.The findings reveal that the Shuixigou Group in the Taibei Sag consists of lithic sandstone.Reservoirs in the group are mostly poor in terms of physical properties,with undeveloped primary pores dominated by intergranular dissolved pores as a result of a strong compaction.Comparative analysis of key controlling factors of the Sangonghe Formation reveals significant distinctions in sandstone particle size,sand body thickness,genesis and distribution,provenance location,and source rock type between the Qiudong area and Shengbei area.Vertically,the coal seams of the Xishanyao Formation exhibit heightened development with shallower burial depth and lower maturity compared to those of the Sangonghe Formation.Consequently,this environment fosters the formation of organic acids,which have a stronger dissolution effect on minerals to develop secondary dissolution pores,and ultimately resulting in better reservoir physical properties.Overall,the reservoirs within the Qiudong area of the Taibei Sag demonstrate superior characteristics compared to those in the Shengbei area.Furthermore,the reservoir physical properties of the Xishanyao Formation are better than those of the Sangonghe Formation.The research findings will provide valuable guidance for the exploration and development of lithological oil and gas reservoirs within the Taibei Sag.展开更多
It is difficult to stimulate coal reservoirs in physical approaches,and the recovery factor of coalbed methane(CBM)can be enhanced by applying strong oxidizers through oxidation to stimulate coal reservoirs.At present...It is difficult to stimulate coal reservoirs in physical approaches,and the recovery factor of coalbed methane(CBM)can be enhanced by applying strong oxidizers through oxidation to stimulate coal reservoirs.At present,however,there have been very few studies on the oxidation of CBM and fewer experimental studies for systematically evaluating the effect of oxidation on the seepage capacity of coal reservoirs.In this paper,the coal samples taken from coal seams of the Jurassic Xishanyao Formation in the Heishan Coal Mine,Toksun,Xinjiang,were selected as the study objects.Hydrogen peroxide solution immersion experiments were carried out on columnar and powdered coal samples,respectively to measure the permeability of columnar coal samples,the dissolution rate of powdered coal samples and the property parameters of hydrogen peroxide solution.Then,the reaction mechanisms between coal samples and hydrogen peroxide and the mechanisms to improve the seepage capacity of coal reservoirs were analyzed by means of X-ray diffraction(XRD),scanning electron microscope(SEM),infrared spectrum and wetting angle measurement.Finally,the stimulation effect of oxidation was compared with that of acidification.The following research results were obtained.(1)The permeability of coal samples is increased significantly after oxidation to 1.4–3.2 times the original permeability.(2)A large number of micro-fractures and dissolved pores are formed in the coal samples after oxidation,and consequently pore connectivity is improved greatly.Thus,the amount of associative hydroxyl and carboxyl functional groups on the surface of the coal samples increases,and the water wettability on the surface reduces.(3)Organic matters and pyrites are oxidized and consumed easily,and the generated H+and micro-molecular aliphatic acids further dissolve inorganic mineral components.(4)Oxidation also has the advantage of acidification for dissolving inorganic mineral components,so there is a low and controllable probability of generating coal powder.In conclusion,applying strong oxidizers has the potential to become a new technology for coal reservoir stimulation.展开更多
The discovery of deep bedrock gas reservoirs in Altun forelands in the Qaidam Basin has expanded a newfield of natural gas exploration and development in China.Since then,it has always been believed that the storage s...The discovery of deep bedrock gas reservoirs in Altun forelands in the Qaidam Basin has expanded a newfield of natural gas exploration and development in China.Since then,it has always been believed that the storage space of this kind of gas reservoirs is composed of well-developed dual media of matrix pores and fractures,but the practices of such gas reservoir development began to be in contradiction with this cognition.In order to achieve a better understanding of the storage space and the main controlling factors of reservoir formation in this bedrock gas reservoir,it is necessary to investigate the dissolved increased pores characteristics and the forced fractures characteristics in the bedrock gas reservoir.Then,based on the data such as cores and cast thin sections in the bedrock intervals in the Dongping 1 and Jiantan 1 blocks,the main storage space types of deep bedrock gas reservoirs in Altun forelands were analyzed,then the main controlling factors of favorable target reservoirs in these blocks were put forward,and in combination with the regional geological background,the geological understandings of favorable target reservoirs and potential reserves were deepened in this study area.The following research results were achieved.(1)The lithology of the bedrock gas reservoirs in this area consists of calc-alkaline igneous rocks and gneiss suite regional metamorphic rocks.Matrix pores are not developed,and their development degree is mainly controlled by faults.Main effective storage spaces and permeable channels are structural fractures and dissolution fractures.(2)The main controlling factors of target reservoir formation include lithology,tectonic effect,weathering,intrusive dikes,and on the whole the rule of ternary-control is followed,namely prevalent lithologyedominant stressesehydrocarbon accumulations in the structural higher parts.(3)The potential zones of reservoir formation include the following 5 types:tectonically stress concentrated tensionetorsional zones,contact zones between lithologic interfaces of intrusive body,weathering zones of compressing uplift,slope sediment zones near circumscribed erosion area,para-conformity or unconformity interface.展开更多
基金supported by the National Science and Technology Major Project of China (Nos. 2011ZX05025-002-02-05)the National Natural Science Foundation of China (Nos. 41202086, 41202087, 41102068)
文摘The large reef complexes of the Upper Permian Changxing Formation, with a significant breakthrough for petroleum exploration, are an important target for petroleum exploration in the Yuanba area of the Sichuan Basin in SW China. The storage space types of reef complexes are dominated by the dissolved pore-fracture（DPF）. However, using only single geophysical methods, it is difficult to predict effective distribution of DPF. Based on a combination of geological models and geophysics technology, this study proposes two new geophysical methods, including anisotropy coherence technique（ACT） and fracture intensity inversion（FII）, to research the characteristics of DPF by faciescontrolling in Changxing Formation in Yuanba area. Two major findings are presented as follows：（1） the characteristics of DPF varying with facies are the result of different diagenetic and petrophysical property. The intensity of DPF decreases from reef and bioclastic bank to interbank sea and slope;（2） ACT can qualitatively identify the distribution of DPF with no-directional and dispersed distribution, while FII can quantitatively characterize the intensity of DPF development within various sedimentary facies. When integrated into the geological study, ACT and FII can provide an effective way to predict the distribution of DPF in similar geological settings and the predicted DPF have been supported by the historical well data.
文摘Very thick, fine-grained quartzose sandstone of the Lower Carboniferous (called the Donghe sandstone) was discovered in Donghe-1 well in the Tarim basin. Highly-productive commercial oil and gas flows were obtained when a well completion test was conducted. This important discovery proved that the quartzose sandstone is a prospecting target with good prospects. After that, other two paying oil and gas flows were found in the Lower Carboniferous in the Tazhong-4 and Tazhong-10 structures (Tazhong means central Tarim), equivalent to the Donghe sandstone. The Tazhong-4 structural oil field is the biggest oil field ever discovered. Therefore it is of guiding importance in oil and gas exploration to deepen the study of sedimentary and reservoir features and the sedimentary environment of the Donghe sandstone and to build a sedimentary model in order to understand the reservoir distribution pattern.
基金funded by the National Natural Science Foundation of China(No.U22B6002)the“14th Five-Year”Forward-looking Basic Science and Technology Project of China National Petroleum Company Limited(No.2022DJ2107).
文摘The positive structure belts surrounding the Taibei Sag,Turpan-Hami Basin,have been the main targets for oil and gas exploration for years and are now left with remaining resources scattering in reservoirs adjacent to source rocks in the sag,where the Shuixigou Group with substantial oil and gas potential constitutes the primary focus for near-source exploration.Consequently,characterization of development and key controlling factors of reservoir space becomes a must for future exploration in the area.This study investigates the development traits,genesis,and controlling factors of the Xishanyao and Sangonghe formations in the Shengbei and Qiudong Sub-sags of the Taibei Sag with techniques such as cast thin-section observation,porosity and permeability tests,high-pressure mercury injection,and saturation fluid NMR analysis of reservoir rocks.The findings reveal that the Shuixigou Group in the Taibei Sag consists of lithic sandstone.Reservoirs in the group are mostly poor in terms of physical properties,with undeveloped primary pores dominated by intergranular dissolved pores as a result of a strong compaction.Comparative analysis of key controlling factors of the Sangonghe Formation reveals significant distinctions in sandstone particle size,sand body thickness,genesis and distribution,provenance location,and source rock type between the Qiudong area and Shengbei area.Vertically,the coal seams of the Xishanyao Formation exhibit heightened development with shallower burial depth and lower maturity compared to those of the Sangonghe Formation.Consequently,this environment fosters the formation of organic acids,which have a stronger dissolution effect on minerals to develop secondary dissolution pores,and ultimately resulting in better reservoir physical properties.Overall,the reservoirs within the Qiudong area of the Taibei Sag demonstrate superior characteristics compared to those in the Shengbei area.Furthermore,the reservoir physical properties of the Xishanyao Formation are better than those of the Sangonghe Formation.The research findings will provide valuable guidance for the exploration and development of lithological oil and gas reservoirs within the Taibei Sag.
基金supported by National Natural Science Foundation of China-General Program“Study on acceleration of gas transmission by enhancing permeability through organic-rich shale fracturing due to oxidation”(No.:51674209).
文摘It is difficult to stimulate coal reservoirs in physical approaches,and the recovery factor of coalbed methane(CBM)can be enhanced by applying strong oxidizers through oxidation to stimulate coal reservoirs.At present,however,there have been very few studies on the oxidation of CBM and fewer experimental studies for systematically evaluating the effect of oxidation on the seepage capacity of coal reservoirs.In this paper,the coal samples taken from coal seams of the Jurassic Xishanyao Formation in the Heishan Coal Mine,Toksun,Xinjiang,were selected as the study objects.Hydrogen peroxide solution immersion experiments were carried out on columnar and powdered coal samples,respectively to measure the permeability of columnar coal samples,the dissolution rate of powdered coal samples and the property parameters of hydrogen peroxide solution.Then,the reaction mechanisms between coal samples and hydrogen peroxide and the mechanisms to improve the seepage capacity of coal reservoirs were analyzed by means of X-ray diffraction(XRD),scanning electron microscope(SEM),infrared spectrum and wetting angle measurement.Finally,the stimulation effect of oxidation was compared with that of acidification.The following research results were obtained.(1)The permeability of coal samples is increased significantly after oxidation to 1.4–3.2 times the original permeability.(2)A large number of micro-fractures and dissolved pores are formed in the coal samples after oxidation,and consequently pore connectivity is improved greatly.Thus,the amount of associative hydroxyl and carboxyl functional groups on the surface of the coal samples increases,and the water wettability on the surface reduces.(3)Organic matters and pyrites are oxidized and consumed easily,and the generated H+and micro-molecular aliphatic acids further dissolve inorganic mineral components.(4)Oxidation also has the advantage of acidification for dissolving inorganic mineral components,so there is a low and controllable probability of generating coal powder.In conclusion,applying strong oxidizers has the potential to become a new technology for coal reservoir stimulation.
基金supported by the Major S&T Special Project of PetroChim Company Limited"Research and application of key exploration and development technologies for constructing highland oilgas fields in the Qaidam Basin"(No.2016-E-01).
文摘The discovery of deep bedrock gas reservoirs in Altun forelands in the Qaidam Basin has expanded a newfield of natural gas exploration and development in China.Since then,it has always been believed that the storage space of this kind of gas reservoirs is composed of well-developed dual media of matrix pores and fractures,but the practices of such gas reservoir development began to be in contradiction with this cognition.In order to achieve a better understanding of the storage space and the main controlling factors of reservoir formation in this bedrock gas reservoir,it is necessary to investigate the dissolved increased pores characteristics and the forced fractures characteristics in the bedrock gas reservoir.Then,based on the data such as cores and cast thin sections in the bedrock intervals in the Dongping 1 and Jiantan 1 blocks,the main storage space types of deep bedrock gas reservoirs in Altun forelands were analyzed,then the main controlling factors of favorable target reservoirs in these blocks were put forward,and in combination with the regional geological background,the geological understandings of favorable target reservoirs and potential reserves were deepened in this study area.The following research results were achieved.(1)The lithology of the bedrock gas reservoirs in this area consists of calc-alkaline igneous rocks and gneiss suite regional metamorphic rocks.Matrix pores are not developed,and their development degree is mainly controlled by faults.Main effective storage spaces and permeable channels are structural fractures and dissolution fractures.(2)The main controlling factors of target reservoir formation include lithology,tectonic effect,weathering,intrusive dikes,and on the whole the rule of ternary-control is followed,namely prevalent lithologyedominant stressesehydrocarbon accumulations in the structural higher parts.(3)The potential zones of reservoir formation include the following 5 types:tectonically stress concentrated tensionetorsional zones,contact zones between lithologic interfaces of intrusive body,weathering zones of compressing uplift,slope sediment zones near circumscribed erosion area,para-conformity or unconformity interface.
