In January 2023,Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oilflow of over 100 cubic meters from the Jurassic channel sandstone for thefirst time,realizing a major breakthrough.In orde...In January 2023,Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oilflow of over 100 cubic meters from the Jurassic channel sandstone for thefirst time,realizing a major breakthrough.In order to provide more support for further oil and gas exploration in this area,this paper analyzes the sedimentary and reservoir characteristics of the Jurassic Lianggaoshan Formation in Bazhong region of northern Sichuan Basin and their control factors based on the exploration achievements of Well Bazhong 1HF.Then,oil and gas reservoir characteristics and oil and gas sources are comparatively analyzed.Finally,the key technologies for the exploration of channel sandstone oil and gas with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity are researched and developed,and the next oil and gas exploration direction in the Lianggaoshan Formation of northern Sichuan Basin is pointed out.And the following research results are obtained.First,in the second member of Lianggaoshan Formation(“Liang 2 Member”for short)in Bazhong region,multi-stage underwater distributary sand bodies of delta front are developed with sandstone thickness of about 25 m and average porosity of 5.6%.The pore types are mainly primary intergranular pores and feldspar/debris intragranular dissolved pores,the pore throat structure is good,and the development of good-quality reservoirs is controlled by the sedimentary microfacies of underwater distributary channel.Second,the oil and gas reservoir of Liang 2 Member is a highly oil-bearing condensate gas reservoir/volatile oil reservoir,whose oil and gas is mainly sourced from the semi-deep lacustrine shale of Liang 1 and 2 Members.Third,channel sand bodies are superimposed and developed continuously in the upper part of Liang 2 and Liang 3 Members,and the source-reservoir configuration is good,with the characteristics of near-source hydrocarbon accumulation and overpressure hydrocarbon enrichment.Fourth,for the channel sandstones with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity,the reservoir prediction technology of“high-frequency sequence stratigraphy slice,seismic frequency decomposition and facies-constrained seismic waveform indication inversion”is developed to precisely characterize the“sweet spot”target of narrow channel sandstone,and the key fracturing technology of“dense cuttingþcomposite temporary pluggingþhigh-intensity proppant injectionþimbibition and oil-increasing”is formed to realize the large-scale reconstruction of channel sandstone reservoir.In conclusion,the breakthrough of Well Bazhong 1HF in the exploration of Lianggaoshan Formation oil and gas in Bazhong region reveals the huge potential of Jurassic oil and gas exploration in the Sichuan Basin,and plays a positive role in promoting the exploration and development of the Jurassic channel sandstone oil and gas in the Sichuan Basin.展开更多
Based on the analysis of core,logging,and testing data,the fourth member of the Cretaceous Quantou Formation(K_(2)q^(4))in the Sanzhao depression,Songliao Basin,is investigated in order to understand the sedimentary c...Based on the analysis of core,logging,and testing data,the fourth member of the Cretaceous Quantou Formation(K_(2)q^(4))in the Sanzhao depression,Songliao Basin,is investigated in order to understand the sedimentary characteristics and hydrocarbon exploration significance of a retrograding shallow-water delta.The results show that during the sedimentary period of K_(2)q^(4),the Sanzhao depression with a gentle basement experienced stable tectonic subsidence and suffered a long-term lake level rise caused by paleoclimate changes(from semiarid to semihumid),the K_(2)q^(4)in the study area were dominated by a fining-upward deltaic succession and had relatively stable thickness.From the bottom to the top,the color of mudstone gradually changes from purplish-red to gray and grayish-green,the contents of caliche nodules decrease gradually,while the presence of pyrite in sediments becomes frequent.Channel sandstones mainly composed of siltstone and fine sandstone with developed high-energy sedimentary structures constitute the main sand bodies of deltaic deposits,but the scale of channel sandstones decrease upward.Despite the long-term lake level rise and fining-upward sedimentary succession,purplish-red mudstone,caliche nodules and thin channel sandstones are still broadly distributed in the study area,and thin channel sandstones can be found at the top of K_(2)q^(4)covered by the black oil shale of Qingshankou Formation.These assertations suggest that the study area was dominated by retrograding shallow-water delta deposits during the sedimentary period of K_(2)q^(4).In comparison with modern Poyang Lake,we infer that during the sedimentary period of K_(2)q^(4),the study area experienced frequent lake level fluctuations triggered by paleoclimate changes despite the long-term lake level rise,and the lake level fluctuations control the deposition of retrograding shallow-water delta.In addition,most of the thin channel sandstones distributed at the top of K_(2)q^(4)and covered by black oil shale are generally immersed in oil,indicating that the thin channel sandstones formed at the top of a retrograding shallow-water delta sedimentary succession are favorable targets for lithological reservoir exploration.展开更多
基金supported by Sinopec Major Scientific and Tech-nology Project“Hydrocarbon accumulation law and distribu-tion prediction in the Sichuan Basin and its surrounding areas”(No.P20059).
文摘In January 2023,Well Bazhong 1HF in the northern Sichuan Basin obtained high-yield industrial oilflow of over 100 cubic meters from the Jurassic channel sandstone for thefirst time,realizing a major breakthrough.In order to provide more support for further oil and gas exploration in this area,this paper analyzes the sedimentary and reservoir characteristics of the Jurassic Lianggaoshan Formation in Bazhong region of northern Sichuan Basin and their control factors based on the exploration achievements of Well Bazhong 1HF.Then,oil and gas reservoir characteristics and oil and gas sources are comparatively analyzed.Finally,the key technologies for the exploration of channel sandstone oil and gas with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity are researched and developed,and the next oil and gas exploration direction in the Lianggaoshan Formation of northern Sichuan Basin is pointed out.And the following research results are obtained.First,in the second member of Lianggaoshan Formation(“Liang 2 Member”for short)in Bazhong region,multi-stage underwater distributary sand bodies of delta front are developed with sandstone thickness of about 25 m and average porosity of 5.6%.The pore types are mainly primary intergranular pores and feldspar/debris intragranular dissolved pores,the pore throat structure is good,and the development of good-quality reservoirs is controlled by the sedimentary microfacies of underwater distributary channel.Second,the oil and gas reservoir of Liang 2 Member is a highly oil-bearing condensate gas reservoir/volatile oil reservoir,whose oil and gas is mainly sourced from the semi-deep lacustrine shale of Liang 1 and 2 Members.Third,channel sand bodies are superimposed and developed continuously in the upper part of Liang 2 and Liang 3 Members,and the source-reservoir configuration is good,with the characteristics of near-source hydrocarbon accumulation and overpressure hydrocarbon enrichment.Fourth,for the channel sandstones with multi-stage vertical superimposition,lateral migration,thin reservoir and strong heterogeneity,the reservoir prediction technology of“high-frequency sequence stratigraphy slice,seismic frequency decomposition and facies-constrained seismic waveform indication inversion”is developed to precisely characterize the“sweet spot”target of narrow channel sandstone,and the key fracturing technology of“dense cuttingþcomposite temporary pluggingþhigh-intensity proppant injectionþimbibition and oil-increasing”is formed to realize the large-scale reconstruction of channel sandstone reservoir.In conclusion,the breakthrough of Well Bazhong 1HF in the exploration of Lianggaoshan Formation oil and gas in Bazhong region reveals the huge potential of Jurassic oil and gas exploration in the Sichuan Basin,and plays a positive role in promoting the exploration and development of the Jurassic channel sandstone oil and gas in the Sichuan Basin.
基金financially supported by the National Science and Technology Major Project of China(H.M.Y.,grant number 2016ZX05013006-006)Natural Science Foundation of Hubei Province of China(L.H.,grant number 2020CFB745)
文摘Based on the analysis of core,logging,and testing data,the fourth member of the Cretaceous Quantou Formation(K_(2)q^(4))in the Sanzhao depression,Songliao Basin,is investigated in order to understand the sedimentary characteristics and hydrocarbon exploration significance of a retrograding shallow-water delta.The results show that during the sedimentary period of K_(2)q^(4),the Sanzhao depression with a gentle basement experienced stable tectonic subsidence and suffered a long-term lake level rise caused by paleoclimate changes(from semiarid to semihumid),the K_(2)q^(4)in the study area were dominated by a fining-upward deltaic succession and had relatively stable thickness.From the bottom to the top,the color of mudstone gradually changes from purplish-red to gray and grayish-green,the contents of caliche nodules decrease gradually,while the presence of pyrite in sediments becomes frequent.Channel sandstones mainly composed of siltstone and fine sandstone with developed high-energy sedimentary structures constitute the main sand bodies of deltaic deposits,but the scale of channel sandstones decrease upward.Despite the long-term lake level rise and fining-upward sedimentary succession,purplish-red mudstone,caliche nodules and thin channel sandstones are still broadly distributed in the study area,and thin channel sandstones can be found at the top of K_(2)q^(4)covered by the black oil shale of Qingshankou Formation.These assertations suggest that the study area was dominated by retrograding shallow-water delta deposits during the sedimentary period of K_(2)q^(4).In comparison with modern Poyang Lake,we infer that during the sedimentary period of K_(2)q^(4),the study area experienced frequent lake level fluctuations triggered by paleoclimate changes despite the long-term lake level rise,and the lake level fluctuations control the deposition of retrograding shallow-water delta.In addition,most of the thin channel sandstones distributed at the top of K_(2)q^(4)and covered by black oil shale are generally immersed in oil,indicating that the thin channel sandstones formed at the top of a retrograding shallow-water delta sedimentary succession are favorable targets for lithological reservoir exploration.
