Optimization of fracturing perforation is of great importance to the commingling gas production in coal measure strata.In this paper,a 3 D lattice algorithm hydraulic fracturing simulator was employed to study the eff...Optimization of fracturing perforation is of great importance to the commingling gas production in coal measure strata.In this paper,a 3 D lattice algorithm hydraulic fracturing simulator was employed to study the effects of perforation position and length on hydraulic fracture propagation in coal measures of the Lin-Xing block,China.Based on field data,three lithologic combinations are simulated:1)a thick section of coal seam sandwiched by sandstones;2)a thin coal seam layer overlay by gas-bearing tight sandstone;3)two coal seams separated by a thin layer of sandstone.Our simulation shows that perforation position and length in multi-layer reservoirs play a major role in hydraulic fracture propagation.Achieving maximum stimulated volume requires consideration of lithologic sequence,coal seam thickness,stress states,and rock properties.To improve the combined gas production in coal measure strata,it is possible to simultaneously stimulate multiple coal seams or adjacent gas-bearing sandstones.In these cases,perforation location and length also significantly impact fracture propagation,and therefore should be carefully designed.Our simulation results using 3 D lattice algorithm are qualitatively consistent with laboratory physical simulation.3 D lattice models can be used to effectively simulate the fracture propagation through layers in coal measure strata.The numerical results provide guidance for perforation optimization in the hydraulic fracturing of coal measure strata.展开更多
Early water breakthrough and a rapid increase in water cut are always observed in high- permeability completion intervals when perforations are uniformly distributed in the wellbore in heterogeneous reservoirs. Optimi...Early water breakthrough and a rapid increase in water cut are always observed in high- permeability completion intervals when perforations are uniformly distributed in the wellbore in heterogeneous reservoirs. Optimization of perforating parameters in partitioned sections in horizontal intervals helps homogenize the inflow from the reservoir and thus is critically important for enhanced oil recovery. This paper derives a coupled reservoir-wellbore flow model based on inflow controlling theory. Genetic algorithms are applied to solving the model as they excel in obtaining the global optimum of discrete functions. The optimized perforating strategy applies a low perforation density in high- permeability intervals and a high perforation density in low-permeability intervals. As a result, the inflow profile is homogenized and idealized.展开更多
In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforatio...In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforation using ANSYS/LS-DYNA simulation technology. The combination of critical perforation parameters for double casing is obtained by studying the influencing factors of the jet-forming process,perforation depth, diameter, and stress changes of the inner and outer casing. The single-target perforation experiments under high-temperature and high-pressure(HTHP) conditions and ground full-scale ring target perforation tests are designed to verify the accuracy of numerical simulation results. The reduced factor is adopted as the quantitative measure of perforation depth and diameter for different types of perforation charge under different conditions. The results show that the perforation depth reduction increases with temperature and pressure, and the reduced factor is between 0.67 and 0.87 under HTHP conditions of 130℃/44 MPa and 137℃/60 MPa. Comparing the results of the numerical simulation and the full-scale test correction, the maximum error is less than 8.91%, and this numerical simulation has strong reliability. This research provides a basis for a reasonable range of double-cased perforation parameters and their optimal selection.展开更多
Currently,unconventional reservoirs are characterized by low single well-controlled reserves,high initial production but fast production decline.This paper sorts out the problems of energy dispersion and limited lengt...Currently,unconventional reservoirs are characterized by low single well-controlled reserves,high initial production but fast production decline.This paper sorts out the problems of energy dispersion and limited length and height of main hydraulic fractures induced in staged multi-cluster fracturing,and proposes an innovative concept of“energy-focused fracturing development”.The technical connotation,theoretical model,and core techniques of energy-focused fracturing development are systematically examined,and the implementation path of this technology is determined.The energy-focused fracturing development technology incorporates the techniques such as geology-engineering integrated design,perforation optimization design,fracturing process design,and drainage engineering control.It transforms the numerous,short and dense hydraulic fractures to limited,long and sparse fractures.It focuses on fracturing energy,and aims to improve the fracture length,height and lateral width,and the proppant long-distance transportation capacity,thus enhancing the single well-controlled reserves and development effect.The energy-focused fracturing development technology has been successfully applied in the carbonate reservoirs in buried hill,shallow coalbed methane reservoirs,and coal-rock gas reservoirs in China,demonstrating the technology's promising application.It is concluded that the energy-focused fracturing development technology can significantly increase the single well production and estimated ultimate recovery(EUR),and will be helpful for efficiently developing low-permeability,unconventional and low-grade resources in China.展开更多
Multi-cluster perforation and multi-staged fracturing of horizontal well is one of the main technologies in volumetric fracturing stimulation of unconventional oil and gas reservoirs,but unconventional reservoirs in C...Multi-cluster perforation and multi-staged fracturing of horizontal well is one of the main technologies in volumetric fracturing stimulation of unconventional oil and gas reservoirs,but unconventional reservoirs in China are generally of strong heterogeneity,which causes different fracture initiation pressures in different positions of lateral,making it difficult to ensure the balanced fracture initiation and propagation between clusters in multi-cluster perforating.It is in urgent need to precisely evaluate the difference in rock strength in lateral and determine the well section with similar rock strength to deploy fractures,so as to reach the goal of balanced stimulation.Based on the drilling and logging data,this paper establishes an unsupervised clustering model of mechanical specific energy of bit at the bottomhole the lateral.Then,the influence of drill string friction,composite drilling and jet-assisted rock breaking on the mechanical specific energy is analyzed,and the distribution and clustering categories of bottomhole mechanical specific energy with decimeter spatial resolution are obtained.Finally,a fracture deployment optimization method for horizontal well volumetric fracturing aiming balanced stimulation is developed by comprehensively considering inter-fracture interference,casing collar position,plug position,and clustering result of bottomhole mechanical specific energy.The following results are obtained.First,compared with brittleness index,Poisson's ratioandstressdifference,perforation erosion area isina strongercorrelationwith themechanical specific energy,andthemechanical specific energy can effectively characterize the difference in the amount of proppant injected into the perforation clusters in the lateral,so it can be served as one of the important indicators for the selection of fracture deployment position.Second,the drilling and logging data cleaning and smoothing and the clustering number selection by the elbow method are the key steps to obtain the clustering results of bottomhole mechanical specific energy,which can tell the difference in the mechanical specific energy with decimeter-level resolution.Third,the interval with mechanical specific energy within 10%of the averagevalue in the section is selected for deploying perforation clusters,and the compiled computer algorithm can automatically determine the optimal position of fracturing section and cluster,so as to realize the differential design of stage spacing and cluster spacing.In conclusion,the research results can further improve the fractures deployment efficiency and balanced stimulation of volumetric fracturing in unconventional oil andgasreservoirs,and this technology is expected to provide ideas andnew methods forthe fracturedeployment optimization of horizontal well volumetric fracturing in unconventional oil and gas reservoirs.展开更多
Based on the framework of BSP, a Hierarchical Bulk Synchronous Parallel (HBSP) performance model is introduced in this paper to capture the per formance optimization problem for various stages in parallel program deve...Based on the framework of BSP, a Hierarchical Bulk Synchronous Parallel (HBSP) performance model is introduced in this paper to capture the per formance optimization problem for various stages in parallel program development and to accurately predict the performance of a parallel program by considering fac tors causing variance at local computation and global communication. The related methodology has been applied to several real applications and the results show that HBSP is a suitable model for optimizing parallel programs.展开更多
基金the financial support by the National Key Research and Development Program of China(Grant No.2020YFC1808102)the Natural Science Foundation of China(No.51874328 and No.52074311)。
文摘Optimization of fracturing perforation is of great importance to the commingling gas production in coal measure strata.In this paper,a 3 D lattice algorithm hydraulic fracturing simulator was employed to study the effects of perforation position and length on hydraulic fracture propagation in coal measures of the Lin-Xing block,China.Based on field data,three lithologic combinations are simulated:1)a thick section of coal seam sandwiched by sandstones;2)a thin coal seam layer overlay by gas-bearing tight sandstone;3)two coal seams separated by a thin layer of sandstone.Our simulation shows that perforation position and length in multi-layer reservoirs play a major role in hydraulic fracture propagation.Achieving maximum stimulated volume requires consideration of lithologic sequence,coal seam thickness,stress states,and rock properties.To improve the combined gas production in coal measure strata,it is possible to simultaneously stimulate multiple coal seams or adjacent gas-bearing sandstones.In these cases,perforation location and length also significantly impact fracture propagation,and therefore should be carefully designed.Our simulation results using 3 D lattice algorithm are qualitatively consistent with laboratory physical simulation.3 D lattice models can be used to effectively simulate the fracture propagation through layers in coal measure strata.The numerical results provide guidance for perforation optimization in the hydraulic fracturing of coal measure strata.
基金supported by National Scientific Project(No. 2008ZX05024-03)
文摘Early water breakthrough and a rapid increase in water cut are always observed in high- permeability completion intervals when perforations are uniformly distributed in the wellbore in heterogeneous reservoirs. Optimization of perforating parameters in partitioned sections in horizontal intervals helps homogenize the inflow from the reservoir and thus is critically important for enhanced oil recovery. This paper derives a coupled reservoir-wellbore flow model based on inflow controlling theory. Genetic algorithms are applied to solving the model as they excel in obtaining the global optimum of discrete functions. The optimized perforating strategy applies a low perforation density in high- permeability intervals and a high perforation density in low-permeability intervals. As a result, the inflow profile is homogenized and idealized.
基金the support of the Foundation of Natural Science Foundation of Shaanxi Province, Grant/ Award nos. 2023-JC-YB-361National Natural Science Foundation (Number 52104033)。
文摘In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforation using ANSYS/LS-DYNA simulation technology. The combination of critical perforation parameters for double casing is obtained by studying the influencing factors of the jet-forming process,perforation depth, diameter, and stress changes of the inner and outer casing. The single-target perforation experiments under high-temperature and high-pressure(HTHP) conditions and ground full-scale ring target perforation tests are designed to verify the accuracy of numerical simulation results. The reduced factor is adopted as the quantitative measure of perforation depth and diameter for different types of perforation charge under different conditions. The results show that the perforation depth reduction increases with temperature and pressure, and the reduced factor is between 0.67 and 0.87 under HTHP conditions of 130℃/44 MPa and 137℃/60 MPa. Comparing the results of the numerical simulation and the full-scale test correction, the maximum error is less than 8.91%, and this numerical simulation has strong reliability. This research provides a basis for a reasonable range of double-cased perforation parameters and their optimal selection.
基金Supported by the PetroChina Scentific and Technological Projects(2023ZZ082023ZZ28)。
文摘Currently,unconventional reservoirs are characterized by low single well-controlled reserves,high initial production but fast production decline.This paper sorts out the problems of energy dispersion and limited length and height of main hydraulic fractures induced in staged multi-cluster fracturing,and proposes an innovative concept of“energy-focused fracturing development”.The technical connotation,theoretical model,and core techniques of energy-focused fracturing development are systematically examined,and the implementation path of this technology is determined.The energy-focused fracturing development technology incorporates the techniques such as geology-engineering integrated design,perforation optimization design,fracturing process design,and drainage engineering control.It transforms the numerous,short and dense hydraulic fractures to limited,long and sparse fractures.It focuses on fracturing energy,and aims to improve the fracture length,height and lateral width,and the proppant long-distance transportation capacity,thus enhancing the single well-controlled reserves and development effect.The energy-focused fracturing development technology has been successfully applied in the carbonate reservoirs in buried hill,shallow coalbed methane reservoirs,and coal-rock gas reservoirs in China,demonstrating the technology's promising application.It is concluded that the energy-focused fracturing development technology can significantly increase the single well production and estimated ultimate recovery(EUR),and will be helpful for efficiently developing low-permeability,unconventional and low-grade resources in China.
基金supported by the Science Fund for Excellent Youth of the National Natural Science Foundation of China"Well hydrodynamics and engineering"(No.52122401).
文摘Multi-cluster perforation and multi-staged fracturing of horizontal well is one of the main technologies in volumetric fracturing stimulation of unconventional oil and gas reservoirs,but unconventional reservoirs in China are generally of strong heterogeneity,which causes different fracture initiation pressures in different positions of lateral,making it difficult to ensure the balanced fracture initiation and propagation between clusters in multi-cluster perforating.It is in urgent need to precisely evaluate the difference in rock strength in lateral and determine the well section with similar rock strength to deploy fractures,so as to reach the goal of balanced stimulation.Based on the drilling and logging data,this paper establishes an unsupervised clustering model of mechanical specific energy of bit at the bottomhole the lateral.Then,the influence of drill string friction,composite drilling and jet-assisted rock breaking on the mechanical specific energy is analyzed,and the distribution and clustering categories of bottomhole mechanical specific energy with decimeter spatial resolution are obtained.Finally,a fracture deployment optimization method for horizontal well volumetric fracturing aiming balanced stimulation is developed by comprehensively considering inter-fracture interference,casing collar position,plug position,and clustering result of bottomhole mechanical specific energy.The following results are obtained.First,compared with brittleness index,Poisson's ratioandstressdifference,perforation erosion area isina strongercorrelationwith themechanical specific energy,andthemechanical specific energy can effectively characterize the difference in the amount of proppant injected into the perforation clusters in the lateral,so it can be served as one of the important indicators for the selection of fracture deployment position.Second,the drilling and logging data cleaning and smoothing and the clustering number selection by the elbow method are the key steps to obtain the clustering results of bottomhole mechanical specific energy,which can tell the difference in the mechanical specific energy with decimeter-level resolution.Third,the interval with mechanical specific energy within 10%of the averagevalue in the section is selected for deploying perforation clusters,and the compiled computer algorithm can automatically determine the optimal position of fracturing section and cluster,so as to realize the differential design of stage spacing and cluster spacing.In conclusion,the research results can further improve the fractures deployment efficiency and balanced stimulation of volumetric fracturing in unconventional oil andgasreservoirs,and this technology is expected to provide ideas andnew methods forthe fracturedeployment optimization of horizontal well volumetric fracturing in unconventional oil and gas reservoirs.
文摘Based on the framework of BSP, a Hierarchical Bulk Synchronous Parallel (HBSP) performance model is introduced in this paper to capture the per formance optimization problem for various stages in parallel program development and to accurately predict the performance of a parallel program by considering fac tors causing variance at local computation and global communication. The related methodology has been applied to several real applications and the results show that HBSP is a suitable model for optimizing parallel programs.
