Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result f...Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result from the sedimentation governed by different sediment sources and sedimentary dynamic conditions in different paleogeographical backgrounds, corresponding to high-frequency sea-level changes. Naturally, this is the fundamental criterion for the classification of genetic types of meter-scale cyclic sequences. The widespread development in stratigraphic records and the regular vertical stacking patterns in long-term sequences, the evolution characters of earth history and the genetic types reflected by specific fabric natures of facies successions in different paleogeographical settings, all that show meter-scale cyclic sequences are not only the elementary working units in stratigraphy and sedimentology, but also the replenishment and extension of parasequence of sequence stratigraphy. Two genetic kinds of facies succession for meter-scale cyclic sequence in neritic-facies strata of carbonate and clastic rocks, are normal grading succession mainly formed by tidal sedimentation and inverse grading succession chiefly made by wave sedimentation, and both of them constitute generally shallowing upward succession, the thickness of which ranges from several tens of centimeters to several meters. The classification of genetic types of meter-scale cyclic sequence could be made in terms of the fabric natures of facies succession, and carbonate meter-scale cyclic sequences could be divided into four types: L-M type, deep-water asymmetrical type, subtidal type and peritidal type. Clastic meter-scale cyclic sequences could be grouped into two types: tidal-dynamic type and wave-dynamic type. The boundaries of meter-scale cyclic sequences are marked by instantaneous punctuated surface formed by non-deposition resulting from high-frequency level changes, which include instantaneous exposed punctuated surface, drowned punctuated surface as well as their relative surface. The development of instantaneous punctuated surface used as the boundary of meter-scale cyclic sequence brings about the limitations of Walter's Law on the explanation of facies distribution in time and space, and reaffirm the importance of Sander's Rule on analysis of stratigraphic records. These non-continuous surface could be traced for long distance and some could be correlative within same basin range. The study of meter-scale cyclic sequences and their regularly vertical stacking patterns in long-term sequences indicate that the research into cyclicity of stratigraphic records is a useful way to get more regularity from stratigraphic records that are frequently complex as well as non-integrated.展开更多
One of the key challenges for underground rock reservoirs is ensuring prevention of the unwanted fluid leakage through rock fracture networks during their service life.Microbial-induced calcium carbonate precipitation...One of the key challenges for underground rock reservoirs is ensuring prevention of the unwanted fluid leakage through rock fracture networks during their service life.Microbial-induced calcium carbonate precipitation(MICP)technology has emerged as a promising bio-healing method for rock fractures with small apertures.In this study,a new“three-stage”injection strategy-based MICP(TS-MICP)bio-healing method was proposed,aiming to achieve a“three-high”performance that includes high bridging rate,high mechanical strength,and high homogeneity.A series of meter-scale rock fracture models were prepared to conduct TS-MICP grouting tests.Compared with the traditional injection strategy-based biohealing methods,the TS-MICP method significantly improved the bridging rate(32.1%e89.5%),mechanical properties(0.138e1.023 MPa),and homogeneity of CaCO_(3)precipitation(334.4%).Additionally,it achieved a higher material utilization rate(1.72 times higher),reducing the consumption of cementation solution(CS)by 258.8%,thereby demonstrating greater potential for field applications.The underlying mechanism for achieving high bridging rate and high homogeneity in CaCO_(3)precipitation can be attributed to the synergistic effects of the coupling injection strategy,which optimizes the advantages at each stage.In stage I,under the influence of gravity,the rapid flocculation and hydrogen bonding interactions of organic matter lead to formation of the dense and high-strength CaCO_(3)precipitation at the bottom using a low-concentration bacterial suspension(BS).This process establishes bridging steps along the wall sides for subsequent uniform CaCO_(3)precipitation.In stage II,concentrated BS is utilized to produce looser CaCO_(3)flocculation,which precipitates uniformly on the pre-existing bridging steps.In stage III,a two-step injection strategy was employed to reinforce the loose CaCO_(3)crystals formed in stages I and II,and finally forms a strong bridging effect with“three-high”performance.展开更多
基金ThestudyisjointlysupportedbyNationalNaturalScienceFoundationofChina (No .4980 2 0 1 2 )andMinistryofSciencesandTechnology (SSER
文摘Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result from the sedimentation governed by different sediment sources and sedimentary dynamic conditions in different paleogeographical backgrounds, corresponding to high-frequency sea-level changes. Naturally, this is the fundamental criterion for the classification of genetic types of meter-scale cyclic sequences. The widespread development in stratigraphic records and the regular vertical stacking patterns in long-term sequences, the evolution characters of earth history and the genetic types reflected by specific fabric natures of facies successions in different paleogeographical settings, all that show meter-scale cyclic sequences are not only the elementary working units in stratigraphy and sedimentology, but also the replenishment and extension of parasequence of sequence stratigraphy. Two genetic kinds of facies succession for meter-scale cyclic sequence in neritic-facies strata of carbonate and clastic rocks, are normal grading succession mainly formed by tidal sedimentation and inverse grading succession chiefly made by wave sedimentation, and both of them constitute generally shallowing upward succession, the thickness of which ranges from several tens of centimeters to several meters. The classification of genetic types of meter-scale cyclic sequence could be made in terms of the fabric natures of facies succession, and carbonate meter-scale cyclic sequences could be divided into four types: L-M type, deep-water asymmetrical type, subtidal type and peritidal type. Clastic meter-scale cyclic sequences could be grouped into two types: tidal-dynamic type and wave-dynamic type. The boundaries of meter-scale cyclic sequences are marked by instantaneous punctuated surface formed by non-deposition resulting from high-frequency level changes, which include instantaneous exposed punctuated surface, drowned punctuated surface as well as their relative surface. The development of instantaneous punctuated surface used as the boundary of meter-scale cyclic sequence brings about the limitations of Walter's Law on the explanation of facies distribution in time and space, and reaffirm the importance of Sander's Rule on analysis of stratigraphic records. These non-continuous surface could be traced for long distance and some could be correlative within same basin range. The study of meter-scale cyclic sequences and their regularly vertical stacking patterns in long-term sequences indicate that the research into cyclicity of stratigraphic records is a useful way to get more regularity from stratigraphic records that are frequently complex as well as non-integrated.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFC3007102)the National Natural Science Foundation of China(Grant Nos.42477188 and 41925012).
文摘One of the key challenges for underground rock reservoirs is ensuring prevention of the unwanted fluid leakage through rock fracture networks during their service life.Microbial-induced calcium carbonate precipitation(MICP)technology has emerged as a promising bio-healing method for rock fractures with small apertures.In this study,a new“three-stage”injection strategy-based MICP(TS-MICP)bio-healing method was proposed,aiming to achieve a“three-high”performance that includes high bridging rate,high mechanical strength,and high homogeneity.A series of meter-scale rock fracture models were prepared to conduct TS-MICP grouting tests.Compared with the traditional injection strategy-based biohealing methods,the TS-MICP method significantly improved the bridging rate(32.1%e89.5%),mechanical properties(0.138e1.023 MPa),and homogeneity of CaCO_(3)precipitation(334.4%).Additionally,it achieved a higher material utilization rate(1.72 times higher),reducing the consumption of cementation solution(CS)by 258.8%,thereby demonstrating greater potential for field applications.The underlying mechanism for achieving high bridging rate and high homogeneity in CaCO_(3)precipitation can be attributed to the synergistic effects of the coupling injection strategy,which optimizes the advantages at each stage.In stage I,under the influence of gravity,the rapid flocculation and hydrogen bonding interactions of organic matter lead to formation of the dense and high-strength CaCO_(3)precipitation at the bottom using a low-concentration bacterial suspension(BS).This process establishes bridging steps along the wall sides for subsequent uniform CaCO_(3)precipitation.In stage II,concentrated BS is utilized to produce looser CaCO_(3)flocculation,which precipitates uniformly on the pre-existing bridging steps.In stage III,a two-step injection strategy was employed to reinforce the loose CaCO_(3)crystals formed in stages I and II,and finally forms a strong bridging effect with“three-high”performance.
