In the Jiaoshiba block of the Fuling shale gas field,the employed reserves and recovery factor by primary well pattern are low,no obvious barrier is found in the development layer series,and layered development is dif...In the Jiaoshiba block of the Fuling shale gas field,the employed reserves and recovery factor by primary well pattern are low,no obvious barrier is found in the development layer series,and layered development is difficult.Based on the understanding of the main factors controlling shale gas enrichment and high production,the theory and technology of shale gas three-dimensional development,such as fine description and modeling of shale gas reservoir,optimization of three-dimensional development strategy,highly efficient drilling with dense well pattern,precision fracturing and real-time control,are discussed.Three-dimensional development refers to the application of optimal and fast drilling and volume fracturing technologies,depending upon the sedimentary characteristics,reservoir characteristics and sweet spot distribution of shale gas,to form"artificial gas reservoir"in a multidimensional space,so as to maximize the employed reserves,recovery factor and yield rate of shale gas development.In the research on shale gas three-dimensional development,the geological+engineering sweet spot description is fundamental,the collaborative optimization of natural fractures and artificial fractures is critical,and the improvement of speed and efficiency in drilling and fracturing engineering is the guarantee.Through the implementation of three-dimensional development,the overall recovery factor in the Jiaoshiba block has increased from 12.6%to 23.3%,providing an important support for the continuous and stable production of the Fuling shale gas field.展开更多
The Fuling shale gas field in China is the largest shale gas field as well as the largest of its type discovered in any Lower Paleozoic formation.In this study,the geology and production of the upper and lower gas lay...The Fuling shale gas field in China is the largest shale gas field as well as the largest of its type discovered in any Lower Paleozoic formation.In this study,the geology and production of the upper and lower gas layers in the Fuling shale gas field are evaluated in terms of structure,shale quality,fault,initial production,and estimated ultimate recovery(EUR).The shale in the lower gas layer of the Jiaoshiba anticline is a high-quality reservoir,where the space is dominated by organic pores in kerogen,and the gas content is high.The shale gas wells reveal relatively high initial production and EUR.However,the shale in the upper gas layer of the Jiaoshiba anticline has reservoir space mainly composed of clay mineral pores and organic pores within bitumen,and the gas content is low.In terms of structure,primary gas migration may occur in the upper gas layer,resulting in free gas accumulation in the structural high,where the development effects are generally better than those in the structural low.The lower gas layer in the Pingqiao anticline,is the main interval for shale gas accumulation and development due to the high-quality shale.Under the influence of faults,the efficiency of exploration wells emplaced on top of the anticline is much lower a compared with those in the flanks.The residual synclines close to the Sichuan Basin,including the Baima and Baitao anticlines,are characterized by more recent uplifts,larger area,greater distance from the deep and large faults,and early fracture closure.Therefore,we recommend that the shale gas exploration and development should be carried out preferentially in areas close to the center of the residual synclines,featuring relatively high-pressure coefficient and moderate burial depth.展开更多
Marine shale gas in South China is widely distributed and demonstrates an enriched resource. Compared with the North American commercial shale gas field, the shale formation in South China is featured by old age, mult...Marine shale gas in South China is widely distributed and demonstrates an enriched resource. Compared with the North American commercial shale gas field, the shale formation in South China is featured by old age, multiple stages tectonic movements, and high thermal evolution degree and complex reservoir forming conditions. As a result, the existing theories and technical methods of exploration in North America cannot be simply applied to South China. Since 2007, based on the in-depth study on a large quantity of analytical test data, we have conducted the theory and technology research for the southern marine shale gas, found Wufeng-Longmaxi Group deep water shelf high-quality shale gas critical parameters coupling laws, proposed the “Binary Enrichment” theory for highly evolved marine shale gas in southern complex tectonic zone, and established a zone selection and evaluation criteria, which are based on the quality of shale, for the key of preservation condition, and for the purpose of economy. Taking this as a guide, we selected Longmaxi formation Lower Silurian of Fuling area in southeastern Sichuan Province as the preferred breakthrough field for the shale gas exploration. The Jiaoye 1 well has the daily gas production of 20.3 × 10<sup>4</sup> m<sup>3</sup>, which embarked the found of China’s first large-scale business development gas field, the Fuling shale gas field. And we submit the first domestic shale gas proven reserves of 1067.5 × 10<sup>8</sup> m<sup>3</sup>. The Fuling shale gas reservoirs are deep water shelf marine high-quality shale, with favorable thickness and even distribution, without dissection in the middle. They are typical self-generation and self-storage shale gas reservoirs. The gas fields have high production gas well;high pressure gas reservoir, good gas components and good exploit results, and there for the Fuling shale gas field is characterized by mid-depth, high pressure, high reservoir pressure, and high quality gas accumulation. Up to March 24, 2014, all of the 101 fracture-gas testing wells have obtained middle and upper shale airflow, with the average single well test production of 32.6 × 10<sup>4</sup> m<sup>3</sup>/d. In the exploration and development process, technology series in geological evaluation, horizontal well, drilling, well completion, piecewise fracturing techniques have been gradually formed. It is of great importance to commercially develop the domestic shale gas and promote the restructuring of China’s energy structure.展开更多
In this paper,a quantitative seismic prediction technique of multi-parameter shale brittleness index suitable for the environment with complex structural stress was developed in order to confirm highly brittle interva...In this paper,a quantitative seismic prediction technique of multi-parameter shale brittleness index suitable for the environment with complex structural stress was developed in order to confirm highly brittle intervals and favorable fracturing zones in the shale reservoirs in the Jiaoshiba Block,Fuling shale gas field,Sichuan Basin.Firstly,the effect of structural compression stress on the brittleness characteristics of rocks were figured out by analyzing structures,mineral composition,development degree of fractures in cores,well logging and seismic data comprehensively.Secondly,according to the Rickman formula,a new brittleness index prediction model based on Young's modulus,Poisson's ratio and shear modulus×density was established by introducing the shear modulus which reflects lateral shear stress-strain.Finally,the quantitative prediction technique of multi-parameter shale brittleness index suitable for the environment with complex structural stress was developed by virtue of the superiority of an elastic rock brittleness index method based on mineral composition to accurately calculate the brittleness index of a full hole.Field application shows that this technique is reliable,since its prediction results coincide with the calculated brittleness index of exploratory wells which are not used for modeling,with a relative error margin below 4%;and that the brittleness index of good shale of Upper Ordovician Wufeng Fm-Lower Silurian Longmaxi Fm in the Jiaoshiba Block increases from the top to the bottom and is stably distributed laterally.Particularly,the Wufeng-Longmaxi 1_(1) is the highest in brittleness index,so it is the most favorable interval for penetrating and fracturing of horizontal wells.展开更多
The Fuling shale gas field in the Sichuan Basin,as a national shale gas demonstration area,is the largest commercially developed shale gas field in the world except those in North America.The fracturing technology in ...The Fuling shale gas field in the Sichuan Basin,as a national shale gas demonstration area,is the largest commercially developed shale gas field in the world except those in North America.The fracturing technology in the mode of“well factory”has been applied widely in the gas field,but it is necessary to perform further investigation on the way to evaluate effectively the fracturing effect of multi-well platform“well factory”and the distribution laws of its induced fracture networks.In this paper,the fractures induced by the“well factory”at the JY 48 platform were real-time monitored by a surfaceedownhole combined microseismic monitoring technology.The geometric size and extension direction of artificial fractures induced in the model of“well factory”fracturing in the Jiaoshiba block of Fuling Shale Gas Field were preliminarily un-derstood.Moreover,the fracturing parameters under the mode of“well factory”were recognized by using the comprehensive interpretation results of surfaceedownhole combined microseismic monitoring technology,together with the SRV fracturing prediction chart.Eventually,the distribution laws of artificial fractures during the“well-factory-zipper”fracturing in the Fuling Shale Gas Field were clarified definitely.This paper provides guidance for the optimization of fracturing parameters at the later stage.展开更多
The core sampling experiments were conducted after hydraulic fracturing in the three-dimensional development zone of Fuling shale gas.Six coring wells of different well types were systematically designed.Based on the ...The core sampling experiments were conducted after hydraulic fracturing in the three-dimensional development zone of Fuling shale gas.Six coring wells of different well types were systematically designed.Based on the integrated engineering technology of post-fracturing drilling,coring and monitoring of shale and the analysis of fracture source tracing,the evaluation of the fracture network after fracturing in the three-dimensional development of shale gas was conducted.The data of core fractures after fracturing indicate that three major types of fractures are formed after fracturing:natural fractures,hydraulic fractures,and fractures induced by external mechanical force,which are further classified into six subcategories:natural structural fractures,natural bedding fractures,hydraulic fractures,hydraulically activated fractures,drilling induced fractures,and fractures induced by core transportation.The forms of the artificial fracture network after fracturing are complex.Hydraulic fractures and hydraulically activated fractures interweave with each other,presenting eight forms of artificial fracture networks,among which the“一”-shaped fracture is the most common,accounting for approximately 70%of the total fractures.When the distance to the fractured wellbore is less than 35 m,the density of the artificial fracture network is relatively high;when it is 35–100 m,the density is lower;and when it is beyond 100 m,the density gradually increases.The results of the fracture tracing in the core sampling area confirm that the current fracturing technology can essentially achieve the differential transformation of the reservoir in the main area of Jiaoshiba block in Fuling.The three-layer three-dimensional development model can efficiently utilize shale gas reserves,although there is still room for improvement in the complexity and propagation uniformity of fractures.It is necessary to further optimize technologies such as close-cutting combined with temporary blocking and deflection within fractures or at fracture mouths,as well as limited flow perforation techniques,to promote the balanced initiation and extension of fractures.展开更多
In order to provide technical support for the shale gas exploration and development in the Lower Silurian Longmaxi Formation of the Sichuan Basin,this paper takes the Longmaxi Formation in the Changning and Fuling Sha...In order to provide technical support for the shale gas exploration and development in the Lower Silurian Longmaxi Formation of the Sichuan Basin,this paper takes the Longmaxi Formation in the Changning and Fuling Shale Gas Fields as the research object to quantitatively characterize the development characteristics of natural fractures in the Longmaxi Formation shale by means of helium pycnometry,X-ray diffraction(XRD),true density testing and other methods,with the aid of the modified petrophysical model.Then,the development types and genetic mechanisms of natural fractures and their influences on shale gas development are discussed.The following research results are obtained.First,the modified petrophysical model can accurately describe the pore system in the Changning shale with a fitting rate of 0.74.Second,the development of natural fractures in shale is different in various regions.The natural fractures in the Changning Shale Gas Field,controlled by basement thrust faults,decollement layers and internal folds,are locally developed and filled with calcareous,and the average fracture porosity is 0.15%.In the Fuling Shale Gas Field,however,natural fractures,mainly controlled by reverse faults and slippage effect,are commonly more developed and unfilled or semi-filled with siliceous,and the average fracture porosity is 1.30%.Third,under the formation conditions,the opening of natural fractures is different.The natural fractures in the Changning Shale Gas Field are basically closed with weaker flowing ability,while those in the Fuling Shale Gas Field are relatively open with stronger flowing ability.Fourth,the occurrence mode of shale gas is influenced by natural fractures,and it is internally dominated by free gas.The initial gas production of shale gas wells is higher.In conclusion,(1)the regression coefficient is introduced to calculate the actual total organic matter content,which promotes the modified petrophysical model to describe matrix pores and fracture pores more accurately;(2)the development of natural fractures in the shale producing pay of the Sichuan Basin is relatively beneficial to shale gas enrichment and exploitation,but the flowing ability of the natural fractures will be weakened under the original formation conditions.展开更多
基金Supported by the Sinopec Science and Technology Project(P22183).
文摘In the Jiaoshiba block of the Fuling shale gas field,the employed reserves and recovery factor by primary well pattern are low,no obvious barrier is found in the development layer series,and layered development is difficult.Based on the understanding of the main factors controlling shale gas enrichment and high production,the theory and technology of shale gas three-dimensional development,such as fine description and modeling of shale gas reservoir,optimization of three-dimensional development strategy,highly efficient drilling with dense well pattern,precision fracturing and real-time control,are discussed.Three-dimensional development refers to the application of optimal and fast drilling and volume fracturing technologies,depending upon the sedimentary characteristics,reservoir characteristics and sweet spot distribution of shale gas,to form"artificial gas reservoir"in a multidimensional space,so as to maximize the employed reserves,recovery factor and yield rate of shale gas development.In the research on shale gas three-dimensional development,the geological+engineering sweet spot description is fundamental,the collaborative optimization of natural fractures and artificial fractures is critical,and the improvement of speed and efficiency in drilling and fracturing engineering is the guarantee.Through the implementation of three-dimensional development,the overall recovery factor in the Jiaoshiba block has increased from 12.6%to 23.3%,providing an important support for the continuous and stable production of the Fuling shale gas field.
基金supported by the National Natural Science Foundation of China(Grant No.41872124 and 91755211)and several Sinopec in-house projects.We thank Sinopec Petroleum Exploration and Production Research Institute,Sinopec Exploration Company,Sinopec Jianghan Oilfield,and Sinopec East China Petroleum Company for valuable data and information.
文摘The Fuling shale gas field in China is the largest shale gas field as well as the largest of its type discovered in any Lower Paleozoic formation.In this study,the geology and production of the upper and lower gas layers in the Fuling shale gas field are evaluated in terms of structure,shale quality,fault,initial production,and estimated ultimate recovery(EUR).The shale in the lower gas layer of the Jiaoshiba anticline is a high-quality reservoir,where the space is dominated by organic pores in kerogen,and the gas content is high.The shale gas wells reveal relatively high initial production and EUR.However,the shale in the upper gas layer of the Jiaoshiba anticline has reservoir space mainly composed of clay mineral pores and organic pores within bitumen,and the gas content is low.In terms of structure,primary gas migration may occur in the upper gas layer,resulting in free gas accumulation in the structural high,where the development effects are generally better than those in the structural low.The lower gas layer in the Pingqiao anticline,is the main interval for shale gas accumulation and development due to the high-quality shale.Under the influence of faults,the efficiency of exploration wells emplaced on top of the anticline is much lower a compared with those in the flanks.The residual synclines close to the Sichuan Basin,including the Baima and Baitao anticlines,are characterized by more recent uplifts,larger area,greater distance from the deep and large faults,and early fracture closure.Therefore,we recommend that the shale gas exploration and development should be carried out preferentially in areas close to the center of the residual synclines,featuring relatively high-pressure coefficient and moderate burial depth.
文摘Marine shale gas in South China is widely distributed and demonstrates an enriched resource. Compared with the North American commercial shale gas field, the shale formation in South China is featured by old age, multiple stages tectonic movements, and high thermal evolution degree and complex reservoir forming conditions. As a result, the existing theories and technical methods of exploration in North America cannot be simply applied to South China. Since 2007, based on the in-depth study on a large quantity of analytical test data, we have conducted the theory and technology research for the southern marine shale gas, found Wufeng-Longmaxi Group deep water shelf high-quality shale gas critical parameters coupling laws, proposed the “Binary Enrichment” theory for highly evolved marine shale gas in southern complex tectonic zone, and established a zone selection and evaluation criteria, which are based on the quality of shale, for the key of preservation condition, and for the purpose of economy. Taking this as a guide, we selected Longmaxi formation Lower Silurian of Fuling area in southeastern Sichuan Province as the preferred breakthrough field for the shale gas exploration. The Jiaoye 1 well has the daily gas production of 20.3 × 10<sup>4</sup> m<sup>3</sup>, which embarked the found of China’s first large-scale business development gas field, the Fuling shale gas field. And we submit the first domestic shale gas proven reserves of 1067.5 × 10<sup>8</sup> m<sup>3</sup>. The Fuling shale gas reservoirs are deep water shelf marine high-quality shale, with favorable thickness and even distribution, without dissection in the middle. They are typical self-generation and self-storage shale gas reservoirs. The gas fields have high production gas well;high pressure gas reservoir, good gas components and good exploit results, and there for the Fuling shale gas field is characterized by mid-depth, high pressure, high reservoir pressure, and high quality gas accumulation. Up to March 24, 2014, all of the 101 fracture-gas testing wells have obtained middle and upper shale airflow, with the average single well test production of 32.6 × 10<sup>4</sup> m<sup>3</sup>/d. In the exploration and development process, technology series in geological evaluation, horizontal well, drilling, well completion, piecewise fracturing techniques have been gradually formed. It is of great importance to commercially develop the domestic shale gas and promote the restructuring of China’s energy structure.
文摘In this paper,a quantitative seismic prediction technique of multi-parameter shale brittleness index suitable for the environment with complex structural stress was developed in order to confirm highly brittle intervals and favorable fracturing zones in the shale reservoirs in the Jiaoshiba Block,Fuling shale gas field,Sichuan Basin.Firstly,the effect of structural compression stress on the brittleness characteristics of rocks were figured out by analyzing structures,mineral composition,development degree of fractures in cores,well logging and seismic data comprehensively.Secondly,according to the Rickman formula,a new brittleness index prediction model based on Young's modulus,Poisson's ratio and shear modulus×density was established by introducing the shear modulus which reflects lateral shear stress-strain.Finally,the quantitative prediction technique of multi-parameter shale brittleness index suitable for the environment with complex structural stress was developed by virtue of the superiority of an elastic rock brittleness index method based on mineral composition to accurately calculate the brittleness index of a full hole.Field application shows that this technique is reliable,since its prediction results coincide with the calculated brittleness index of exploratory wells which are not used for modeling,with a relative error margin below 4%;and that the brittleness index of good shale of Upper Ordovician Wufeng Fm-Lower Silurian Longmaxi Fm in the Jiaoshiba Block increases from the top to the bottom and is stably distributed laterally.Particularly,the Wufeng-Longmaxi 1_(1) is the highest in brittleness index,so it is the most favorable interval for penetrating and fracturing of horizontal wells.
基金Supported by the Sinopec Key Science and Technology Projects“Fuling shale gas stimulations”(Grant No.P14092)“Fuling shale gas development techniques”(Grant No.P13053).
文摘The Fuling shale gas field in the Sichuan Basin,as a national shale gas demonstration area,is the largest commercially developed shale gas field in the world except those in North America.The fracturing technology in the mode of“well factory”has been applied widely in the gas field,but it is necessary to perform further investigation on the way to evaluate effectively the fracturing effect of multi-well platform“well factory”and the distribution laws of its induced fracture networks.In this paper,the fractures induced by the“well factory”at the JY 48 platform were real-time monitored by a surfaceedownhole combined microseismic monitoring technology.The geometric size and extension direction of artificial fractures induced in the model of“well factory”fracturing in the Jiaoshiba block of Fuling Shale Gas Field were preliminarily un-derstood.Moreover,the fracturing parameters under the mode of“well factory”were recognized by using the comprehensive interpretation results of surfaceedownhole combined microseismic monitoring technology,together with the SRV fracturing prediction chart.Eventually,the distribution laws of artificial fractures during the“well-factory-zipper”fracturing in the Fuling Shale Gas Field were clarified definitely.This paper provides guidance for the optimization of fracturing parameters at the later stage.
文摘The core sampling experiments were conducted after hydraulic fracturing in the three-dimensional development zone of Fuling shale gas.Six coring wells of different well types were systematically designed.Based on the integrated engineering technology of post-fracturing drilling,coring and monitoring of shale and the analysis of fracture source tracing,the evaluation of the fracture network after fracturing in the three-dimensional development of shale gas was conducted.The data of core fractures after fracturing indicate that three major types of fractures are formed after fracturing:natural fractures,hydraulic fractures,and fractures induced by external mechanical force,which are further classified into six subcategories:natural structural fractures,natural bedding fractures,hydraulic fractures,hydraulically activated fractures,drilling induced fractures,and fractures induced by core transportation.The forms of the artificial fracture network after fracturing are complex.Hydraulic fractures and hydraulically activated fractures interweave with each other,presenting eight forms of artificial fracture networks,among which the“一”-shaped fracture is the most common,accounting for approximately 70%of the total fractures.When the distance to the fractured wellbore is less than 35 m,the density of the artificial fracture network is relatively high;when it is 35–100 m,the density is lower;and when it is beyond 100 m,the density gradually increases.The results of the fracture tracing in the core sampling area confirm that the current fracturing technology can essentially achieve the differential transformation of the reservoir in the main area of Jiaoshiba block in Fuling.The three-layer three-dimensional development model can efficiently utilize shale gas reserves,although there is still room for improvement in the complexity and propagation uniformity of fractures.It is necessary to further optimize technologies such as close-cutting combined with temporary blocking and deflection within fractures or at fracture mouths,as well as limited flow perforation techniques,to promote the balanced initiation and extension of fractures.
基金Project supported by the National Major Science and Technology Project“Formation and Enrichment Conditions of Shale Gas in the Sichuan Basin and Its Surrounding Areas,Technologies for Selecting Regions,Evaluation and Applications”(No.:2017ZX05035)。
文摘In order to provide technical support for the shale gas exploration and development in the Lower Silurian Longmaxi Formation of the Sichuan Basin,this paper takes the Longmaxi Formation in the Changning and Fuling Shale Gas Fields as the research object to quantitatively characterize the development characteristics of natural fractures in the Longmaxi Formation shale by means of helium pycnometry,X-ray diffraction(XRD),true density testing and other methods,with the aid of the modified petrophysical model.Then,the development types and genetic mechanisms of natural fractures and their influences on shale gas development are discussed.The following research results are obtained.First,the modified petrophysical model can accurately describe the pore system in the Changning shale with a fitting rate of 0.74.Second,the development of natural fractures in shale is different in various regions.The natural fractures in the Changning Shale Gas Field,controlled by basement thrust faults,decollement layers and internal folds,are locally developed and filled with calcareous,and the average fracture porosity is 0.15%.In the Fuling Shale Gas Field,however,natural fractures,mainly controlled by reverse faults and slippage effect,are commonly more developed and unfilled or semi-filled with siliceous,and the average fracture porosity is 1.30%.Third,under the formation conditions,the opening of natural fractures is different.The natural fractures in the Changning Shale Gas Field are basically closed with weaker flowing ability,while those in the Fuling Shale Gas Field are relatively open with stronger flowing ability.Fourth,the occurrence mode of shale gas is influenced by natural fractures,and it is internally dominated by free gas.The initial gas production of shale gas wells is higher.In conclusion,(1)the regression coefficient is introduced to calculate the actual total organic matter content,which promotes the modified petrophysical model to describe matrix pores and fracture pores more accurately;(2)the development of natural fractures in the shale producing pay of the Sichuan Basin is relatively beneficial to shale gas enrichment and exploitation,but the flowing ability of the natural fractures will be weakened under the original formation conditions.
