Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest Chin...Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality （2-3 orders of magnitude at the intersection zone） and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.展开更多
The Silurian Kepingtage Formation in Tazhong area is regarded as an acid-sensitive hydrocarbon reservoir. However, formation mechanism of acid-sensitive of the reservoir cannot be interpreted by the existing acid-sens...The Silurian Kepingtage Formation in Tazhong area is regarded as an acid-sensitive hydrocarbon reservoir. However, formation mechanism of acid-sensitive of the reservoir cannot be interpreted by the existing acid-sensitive evaluation criterion based on damage rate. The contents of acid-sensitive minerals illustrated by bulk-rock XRD, scanning electron microscopy and clay mineral composition analysis exert the dominant control on acid-sensitive flow testing of the reservoir. The ironbearing minerals（including pyrite cements and chlorite cements） mainly deteriorate reservoir quality, while the iron-free minerals（including calcite cements and dolomite cements） mainly improve permeability. The permeability variation of the tested samples is controlled by the relative content of two acid-sensitive minerals. On the basis of newly established sensitivity mechanism and its influence on permeability, the corresponding ion（Fe^（2＋）） stabilizer was added to the acidizing fluids during the acidification reconstruction, which inhibited the negative factors of acid-sensitive minerals and improved the target layer quality effectively.展开更多
In order to predict favorable exploration areas of the Paleozoic, Carboniferous and Silurian clastic reservoirs in the Tazhong area of the Tarim Basin, west China, we studied the basic characteristics of Paleozoic cla...In order to predict favorable exploration areas of the Paleozoic, Carboniferous and Silurian clastic reservoirs in the Tazhong area of the Tarim Basin, west China, we studied the basic characteristics of Paleozoic clastic reservoirs in the Tazhong area based on a lot of data. Several issues about the hydrocarbon accumulation related to the reservoirs were also discussed. The results were concluded that： the high-value areas of the porosity and permeability of clastic reservoirs were located in the southeast of the Tazhong area; the content of cement （carbonate cement in particular） was the main factor controlling the porosity and permeability of clastic reservoirs; the hydrocarbon distributions of Carboniferous and Silurian clastic reservoirs were closely related to the porosity and permeability; the favorable hydrocarbon accumulation areas of the two sets of strata were located in the southeast of this area, especially in the updip pinch-out area.展开更多
Gas washing has been known in the Tazhong area of the Tarim Basin,but its quantitative assessment has not yet been reported.Here the influence of gas washing fractionation in the area was discussed based on the gas ch...Gas washing has been known in the Tazhong area of the Tarim Basin,but its quantitative assessment has not yet been reported.Here the influence of gas washing fractionation in the area was discussed based on the gas chromatogram data of 68 oils and the results of the mixing experiments of a black oil and a condensate.The results show that the intensity of gas washing fractionation decreased generally from northern to southern part and vertically from deep reservoirs to shallow reservoirs.The gas washing fractionation was mainly controlled by fault systems in this area,with the increase of n-alkane mass depletion positively correlated to the number and scale of faults.Gas washing fractionation appears to have affected the hydrocarbon property,and as a result the diversity of the crude oils is markedly controlled by gas washing.In addition,the occurrence of waxy oil in this area may be resulted from multiple factors including gas washing,mixed filling and migration fractionation.展开更多
According to the assemblage characteristics of saturated hydrocarbon biomarkers in crude oils and their geochemical implications, this study has proposed, for the first time, the criteria for the genetic classificatio...According to the assemblage characteristics of saturated hydrocarbon biomarkers in crude oils and their geochemical implications, this study has proposed, for the first time, the criteria for the genetic classification of crude oils in the Tazhong area of the Tarim Basin, China. Crude oils from the area studied are classified as three genetic types: type-I is characterized by the low contents of C29 norhopane, extremely abundant contents of gammacerane, low contents of rearranged sterane and relatively high contents of regular C28 sterane; the geochemical properties of type-II crude oils are opposite to those of type-I crude oils; the parameters for type-III crude oils are intermediate between type-I and type-II. Results of oil correlation indicated that type-I crude oils were derived from Cambrian-Lower Ordovician hydrocarbon source rocks, type-II curde oils originated from Middle-Upper Ordovician hydrocarbon source rocks and type-III crude oils are of mixed origin.展开更多
基金supported by the National 973 Basic Research Program (Grant No.2006CB202308)the Major National Science & Technology Program (2008ZX05008-004-012)
文摘Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality （2-3 orders of magnitude at the intersection zone） and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.
基金supported by the National Science and Technology Major Project of China(Grant No.2017ZX05008003-050)the PetroChina Innovation Foundation(Grant No.2016D-5007-0104)+1 种基金the Yangtze Youth Talents Fund(Grant No.2015cqr08)the Yangtze Fund for Youth Teams of Science and Technology Innovation(Grant No.2015cqt04)
文摘The Silurian Kepingtage Formation in Tazhong area is regarded as an acid-sensitive hydrocarbon reservoir. However, formation mechanism of acid-sensitive of the reservoir cannot be interpreted by the existing acid-sensitive evaluation criterion based on damage rate. The contents of acid-sensitive minerals illustrated by bulk-rock XRD, scanning electron microscopy and clay mineral composition analysis exert the dominant control on acid-sensitive flow testing of the reservoir. The ironbearing minerals（including pyrite cements and chlorite cements） mainly deteriorate reservoir quality, while the iron-free minerals（including calcite cements and dolomite cements） mainly improve permeability. The permeability variation of the tested samples is controlled by the relative content of two acid-sensitive minerals. On the basis of newly established sensitivity mechanism and its influence on permeability, the corresponding ion（Fe^（2＋）） stabilizer was added to the acidizing fluids during the acidification reconstruction, which inhibited the negative factors of acid-sensitive minerals and improved the target layer quality effectively.
基金supported by the Basic Research Program of China (973 Program, Grant No. 2006CB202308)
文摘In order to predict favorable exploration areas of the Paleozoic, Carboniferous and Silurian clastic reservoirs in the Tazhong area of the Tarim Basin, west China, we studied the basic characteristics of Paleozoic clastic reservoirs in the Tazhong area based on a lot of data. Several issues about the hydrocarbon accumulation related to the reservoirs were also discussed. The results were concluded that： the high-value areas of the porosity and permeability of clastic reservoirs were located in the southeast of the Tazhong area; the content of cement （carbonate cement in particular） was the main factor controlling the porosity and permeability of clastic reservoirs; the hydrocarbon distributions of Carboniferous and Silurian clastic reservoirs were closely related to the porosity and permeability; the favorable hydrocarbon accumulation areas of the two sets of strata were located in the southeast of this area, especially in the updip pinch-out area.
基金Supported by National Basic Research Program of China (Grant No.2006CB202303)the National Natural Science Foundation of China (Grant No.40672091)
文摘Gas washing has been known in the Tazhong area of the Tarim Basin,but its quantitative assessment has not yet been reported.Here the influence of gas washing fractionation in the area was discussed based on the gas chromatogram data of 68 oils and the results of the mixing experiments of a black oil and a condensate.The results show that the intensity of gas washing fractionation decreased generally from northern to southern part and vertically from deep reservoirs to shallow reservoirs.The gas washing fractionation was mainly controlled by fault systems in this area,with the increase of n-alkane mass depletion positively correlated to the number and scale of faults.Gas washing fractionation appears to have affected the hydrocarbon property,and as a result the diversity of the crude oils is markedly controlled by gas washing.In addition,the occurrence of waxy oil in this area may be resulted from multiple factors including gas washing,mixed filling and migration fractionation.
基金This research was funded by the State "Tenth Five-Year Plan" Key Science and Technology Program (2004BA616A02-01-01-03).
文摘According to the assemblage characteristics of saturated hydrocarbon biomarkers in crude oils and their geochemical implications, this study has proposed, for the first time, the criteria for the genetic classification of crude oils in the Tazhong area of the Tarim Basin, China. Crude oils from the area studied are classified as three genetic types: type-I is characterized by the low contents of C29 norhopane, extremely abundant contents of gammacerane, low contents of rearranged sterane and relatively high contents of regular C28 sterane; the geochemical properties of type-II crude oils are opposite to those of type-I crude oils; the parameters for type-III crude oils are intermediate between type-I and type-II. Results of oil correlation indicated that type-I crude oils were derived from Cambrian-Lower Ordovician hydrocarbon source rocks, type-II curde oils originated from Middle-Upper Ordovician hydrocarbon source rocks and type-III crude oils are of mixed origin.
