We applied the material balance principle of the denudation volume and sedimentary flux to study the denudation-accumulation system between the Longmen Mountains （Mts.） and the foreland basin. The amount of sediment...We applied the material balance principle of the denudation volume and sedimentary flux to study the denudation-accumulation system between the Longmen Mountains （Mts.） and the foreland basin. The amount of sediment in each sedimentation stage of the basin was estimated to obtain the denudation volume, erosion thickness and deposit thickness since the Late Triassic Epoch, to enable us to recover the paleoelevation of the provenance and the sedimentary area. The results show the following： （1） Since the Late Triassic Epoch, the elevation of the surface of the Longmen Mts. has uplifted from 0 m to 2751 m, and the crust of the Longmen Mts. has uplifted by 9.8 km. Approximately 72% of the materials introduced have been denuded from the mountains. （2） It is difficult to recover the paleoelevation of each stage of the Longmen Mts. foreland basin quantitatively by the present-day techniques and data. （3） The formation of the Longmen Mts. foreland basin consisted of three stages of thrust belt tectonic load and three stages of thrust belt erosional unload. During tectonic loading stages （Late Triassic Epoch, Late Jurassic-Early Cretaceous, Late Cretaceous-Miocene）, the average elevation of Longmen Mts. was lower （approximately 700-1700 m）. During erosional unloading stages （Early and Middle Jurassic, Middle Cretaceous and Jiaguan, Late Cenozoic）, the average elevation of Longmen Mts. was high at approximately 2000-2800m.展开更多
It is difficult to determine the effective reservoir rock compressibility,aquifer volume and water influx of high pressure and ultra-high pressure gas reservoirs,so when the traditional apparent reservoir pressure and...It is difficult to determine the effective reservoir rock compressibility,aquifer volume and water influx of high pressure and ultra-high pressure gas reservoirs,so when the traditional apparent reservoir pressure and cumulative gas production curve extrapolation method and its modified version are used to calculate the initial gas in-place of such gas reservoirs,the calculation accuracy is lower.The material balance equation in the form of power function for such gas reservoirs was established based on Gonzalez method to improve the accuracy and reliability of reserve evaluation.Then,based on 20 high pressure and ultra-high pressure reservoirs that had been developed abroad,the empirical value of the power exponent was defined,and the influences of the depletion degree of apparent reservoir pressure and the degree of reserve recovery on the reliability of reserve calculation were analyzed.Besides,the critical value of the key parameter affecting the reliability of reserve evaluation(depletion degree of apparent reservoir pressure)was determined and compared with the critical value of the two-linear trends.Finally,an example calculation was carried out.And the following research results were obtained.First,the empirical value of the power exponent calculated using the material balance method in the form of power function is 1.02847,with an upper limit of 1.11567.Second,the depletion degree of apparent reservoir pressure corresponding to the inflection point of the classical two-linear trends ranges from 0.14 to 0.38 with an average of 0.23,while that corresponding to the extrapolation point of the second straight line is between 0.23 and 0.50 with an average of 0.33,and the corresponding degree of reserve recovery is in the range of 33%-65%with an average of 45%.Third,the reserves of such high pressure gas reservoirs calculated with this new method has an error rate less than 10%if the depletion degree of apparent reservoir pressure is greater than 0.33.In conclusion,for such high pressure gas reservoirs and the stress-sensitive fractured gas reservoirs,the material balance method in the form of power function proposed in this paper can avoid the uncertainty parameters(e.g.effective reservoir rock compressibility,aquifer volume and water influx)and it is advantageous with simple calculation process,better practicability and small error.展开更多
In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-...In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-uniformity degree of reservoir physical properties and the activity degree of peripheral water,respectively,based on the dual mechanism of water invasion to recharge the formation energy and seal off the gas in the reservoir.Then,the material balance method considering the phenomenon of water sealed gas was established.On this basis,the water invasion characteristic curve chart of water-bearing gas reservoirs was plotted,and the non-uniform water invasion mode was classified based on the example gas reservoir.And the following research results were obtained.First,in the water invasion characteristic curve chart of waterbearing gas reservoirs which is plotted based on the material balance method considering the influence of water sealed gas,the upper right area and the lower left area are defined as recharge area and seal area,respectively.By taking A=0 and B=2 as the boundary,the recharge area is divided into strong recharge area and weak recharge area.By taking A=2 and B=2 as the boundary,the seal area is divided into strong seal area and weak seal area.And correspondingly there are four water invasion modes,i.e.,strong recharge,weak recharge,weak seal and strong seal.Second,for fractured gas reservoirs,the non-uniformity degree of reservoir physical properties is high,and water sealed gas can be formed easily after water invasion.The dimensionless relative pseudo-pressure data of this type of gas reservoir is located in the seal area of the water invasion characteristic curve chart.Third,for the gas reservoirs whose reservoir physical properties are relatively uniform,the dimensionless relative pseudo-pressure data is located in the recharge area of the water invasion characteristic curve chart,and the recharge effect of water invasion on formation energy is greater than the weakening effect of water sealed gas on formation energy.Fourth,with the increase of A,the non-uniformity degree of reservoir physical properties increases,the water invasion characteristic curve shifts from the upper right to the lower left,and the recovery factor of gas reservoir decreases continuously.With the increase of B,the recharge effect of water invasion on formation energy and the weakening effect of water sealed gas on formation energy are both weakened,the distribution range of water invasion characteristic curve narrows to the recharge/seal boundary,and the corresponding range of gas reservoir recovery factor also narrows.展开更多
Ultra-deepmajor gas fields are typically characterized by high and ultra-high pressure,tightmatrix and developed fractures,so the reserve estimation is of higher uncertainty.In order to accurately estimate the reserve...Ultra-deepmajor gas fields are typically characterized by high and ultra-high pressure,tightmatrix and developed fractures,so the reserve estimation is of higher uncertainty.In order to accurately estimate the reserves of this type of gas reservoir,this paper analyzed the correlation between the effective rock compressibility and the cumulative effective rock compressibility based on the material balance equation of high and ultra-high pressure gas reservoirs,and accordingly selected the material balance based analysis method suitable for the reserves estimation of high and ultra-high pressure gas reservoirs.Then,the starting calculation conditions of reserve estimation were determined using the non-linear regressionmethod.In addition,a semilogarithmic type curvematchingmethodwas established for the caseswhere the starting conditions could not bemet.Finally,thismethodwas applied to calculate the reserves of three ultra-high pressure gas fields(reservoirs)to verify its reliability.And the following research results were obtained.First,the cumulative effective compressibility of gas reservoir in thematerial balance equation of high and ultra-high pressure gas reservoir is a key parameter influencing its reserves,and it is the function of original formation pressure and current average formation pressure,but its numerical value can be hardly obtained by core experiments.Second,it is recommended to adopt the nonlinear regressionmethod without compressibility to estimate the reserves of high and ultra-high pressure gas reservoirs.Third,the calculation starting point of reserves by the nonlinear regression method(the starting point of dimensionless apparent formation pressure-cumulative gas production curve deviating from the straight line relationship)cannot be theoretically calculated.The calculation starting point for different dimensionless linear coefficients(uD)obtained fromthe statistical results by the graphic method corresponds to the dimensionless apparent pressure depletion degree of 0.06-0.38,and that obtained based on the data statistics of the example gas reservoir falls within this interval.Fourth,when the starting conditions are not satisfied,the semi-logarithmic type curve matching method can be used for reserve estimation.The ratio of the reserves to the apparent geological reservesG/G_(app) is a function of uD.The higher the uD,the lower the G/G_(app).Fifth,for the high and ultra-high pressure gas reservoirs in the production test stage,the test production time shall be extended as long as possible to improve the reliability of reserve estimation.And for those in the middle and late stages of development,it is necessary to prepare the comprehensive treatment measures on the basis of reserves so as to improve the development effects of gas reservoirs continuously.展开更多
This paper presents two methods for easy determination of water influx in reservoirs based on the material balance theory of reservoirs,i.e.,the Net Production Volume Curve,and the Production Index Curve.These methods...This paper presents two methods for easy determination of water influx in reservoirs based on the material balance theory of reservoirs,i.e.,the Net Production Volume Curve,and the Production Index Curve.These methods can be used for esti-ma tion of water influx in reservoirs without any assumption of aquifer shape and size by applying the production performance data.Hence the tedium of the c onventional trial-and-error calculations and obvious uncertainty could be over come in ap plication of the easy and practical new methods.展开更多
基金the Project of the National Natural Science Foudation of China (Grant No.41372114,41340005,41172162,40972083)
文摘We applied the material balance principle of the denudation volume and sedimentary flux to study the denudation-accumulation system between the Longmen Mountains （Mts.） and the foreland basin. The amount of sediment in each sedimentation stage of the basin was estimated to obtain the denudation volume, erosion thickness and deposit thickness since the Late Triassic Epoch, to enable us to recover the paleoelevation of the provenance and the sedimentary area. The results show the following： （1） Since the Late Triassic Epoch, the elevation of the surface of the Longmen Mts. has uplifted from 0 m to 2751 m, and the crust of the Longmen Mts. has uplifted by 9.8 km. Approximately 72% of the materials introduced have been denuded from the mountains. （2） It is difficult to recover the paleoelevation of each stage of the Longmen Mts. foreland basin quantitatively by the present-day techniques and data. （3） The formation of the Longmen Mts. foreland basin consisted of three stages of thrust belt tectonic load and three stages of thrust belt erosional unload. During tectonic loading stages （Late Triassic Epoch, Late Jurassic-Early Cretaceous, Late Cretaceous-Miocene）, the average elevation of Longmen Mts. was lower （approximately 700-1700 m）. During erosional unloading stages （Early and Middle Jurassic, Middle Cretaceous and Jiaguan, Late Cenozoic）, the average elevation of Longmen Mts. was high at approximately 2000-2800m.
基金Project supported by Major Special Science and Technology Project of PetroChina Company Limited“Study and application of key technologies for developing deepeultra-deep gas in Kuqa depression”(No.:2018E-1803).
文摘It is difficult to determine the effective reservoir rock compressibility,aquifer volume and water influx of high pressure and ultra-high pressure gas reservoirs,so when the traditional apparent reservoir pressure and cumulative gas production curve extrapolation method and its modified version are used to calculate the initial gas in-place of such gas reservoirs,the calculation accuracy is lower.The material balance equation in the form of power function for such gas reservoirs was established based on Gonzalez method to improve the accuracy and reliability of reserve evaluation.Then,based on 20 high pressure and ultra-high pressure reservoirs that had been developed abroad,the empirical value of the power exponent was defined,and the influences of the depletion degree of apparent reservoir pressure and the degree of reserve recovery on the reliability of reserve calculation were analyzed.Besides,the critical value of the key parameter affecting the reliability of reserve evaluation(depletion degree of apparent reservoir pressure)was determined and compared with the critical value of the two-linear trends.Finally,an example calculation was carried out.And the following research results were obtained.First,the empirical value of the power exponent calculated using the material balance method in the form of power function is 1.02847,with an upper limit of 1.11567.Second,the depletion degree of apparent reservoir pressure corresponding to the inflection point of the classical two-linear trends ranges from 0.14 to 0.38 with an average of 0.23,while that corresponding to the extrapolation point of the second straight line is between 0.23 and 0.50 with an average of 0.33,and the corresponding degree of reserve recovery is in the range of 33%-65%with an average of 45%.Third,the reserves of such high pressure gas reservoirs calculated with this new method has an error rate less than 10%if the depletion degree of apparent reservoir pressure is greater than 0.33.In conclusion,for such high pressure gas reservoirs and the stress-sensitive fractured gas reservoirs,the material balance method in the form of power function proposed in this paper can avoid the uncertainty parameters(e.g.effective reservoir rock compressibility,aquifer volume and water influx)and it is advantageous with simple calculation process,better practicability and small error.
基金Project supported by the PetroChina-SWPU Innovation Alliance's technological cooperation project(No.2020CX010402).
文摘In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-uniformity degree of reservoir physical properties and the activity degree of peripheral water,respectively,based on the dual mechanism of water invasion to recharge the formation energy and seal off the gas in the reservoir.Then,the material balance method considering the phenomenon of water sealed gas was established.On this basis,the water invasion characteristic curve chart of water-bearing gas reservoirs was plotted,and the non-uniform water invasion mode was classified based on the example gas reservoir.And the following research results were obtained.First,in the water invasion characteristic curve chart of waterbearing gas reservoirs which is plotted based on the material balance method considering the influence of water sealed gas,the upper right area and the lower left area are defined as recharge area and seal area,respectively.By taking A=0 and B=2 as the boundary,the recharge area is divided into strong recharge area and weak recharge area.By taking A=2 and B=2 as the boundary,the seal area is divided into strong seal area and weak seal area.And correspondingly there are four water invasion modes,i.e.,strong recharge,weak recharge,weak seal and strong seal.Second,for fractured gas reservoirs,the non-uniformity degree of reservoir physical properties is high,and water sealed gas can be formed easily after water invasion.The dimensionless relative pseudo-pressure data of this type of gas reservoir is located in the seal area of the water invasion characteristic curve chart.Third,for the gas reservoirs whose reservoir physical properties are relatively uniform,the dimensionless relative pseudo-pressure data is located in the recharge area of the water invasion characteristic curve chart,and the recharge effect of water invasion on formation energy is greater than the weakening effect of water sealed gas on formation energy.Fourth,with the increase of A,the non-uniformity degree of reservoir physical properties increases,the water invasion characteristic curve shifts from the upper right to the lower left,and the recovery factor of gas reservoir decreases continuously.With the increase of B,the recharge effect of water invasion on formation energy and the weakening effect of water sealed gas on formation energy are both weakened,the distribution range of water invasion characteristic curve narrows to the recharge/seal boundary,and the corresponding range of gas reservoir recovery factor also narrows.
基金supported by the Major Science and Technology Project of PetroChina Company Limited“Research and Application of Key Technologies for Development of Deep and Ultra-deep Gas Fields in Kuqa Depression”(No.2018E-1803).
文摘Ultra-deepmajor gas fields are typically characterized by high and ultra-high pressure,tightmatrix and developed fractures,so the reserve estimation is of higher uncertainty.In order to accurately estimate the reserves of this type of gas reservoir,this paper analyzed the correlation between the effective rock compressibility and the cumulative effective rock compressibility based on the material balance equation of high and ultra-high pressure gas reservoirs,and accordingly selected the material balance based analysis method suitable for the reserves estimation of high and ultra-high pressure gas reservoirs.Then,the starting calculation conditions of reserve estimation were determined using the non-linear regressionmethod.In addition,a semilogarithmic type curvematchingmethodwas established for the caseswhere the starting conditions could not bemet.Finally,thismethodwas applied to calculate the reserves of three ultra-high pressure gas fields(reservoirs)to verify its reliability.And the following research results were obtained.First,the cumulative effective compressibility of gas reservoir in thematerial balance equation of high and ultra-high pressure gas reservoir is a key parameter influencing its reserves,and it is the function of original formation pressure and current average formation pressure,but its numerical value can be hardly obtained by core experiments.Second,it is recommended to adopt the nonlinear regressionmethod without compressibility to estimate the reserves of high and ultra-high pressure gas reservoirs.Third,the calculation starting point of reserves by the nonlinear regression method(the starting point of dimensionless apparent formation pressure-cumulative gas production curve deviating from the straight line relationship)cannot be theoretically calculated.The calculation starting point for different dimensionless linear coefficients(uD)obtained fromthe statistical results by the graphic method corresponds to the dimensionless apparent pressure depletion degree of 0.06-0.38,and that obtained based on the data statistics of the example gas reservoir falls within this interval.Fourth,when the starting conditions are not satisfied,the semi-logarithmic type curve matching method can be used for reserve estimation.The ratio of the reserves to the apparent geological reservesG/G_(app) is a function of uD.The higher the uD,the lower the G/G_(app).Fifth,for the high and ultra-high pressure gas reservoirs in the production test stage,the test production time shall be extended as long as possible to improve the reliability of reserve estimation.And for those in the middle and late stages of development,it is necessary to prepare the comprehensive treatment measures on the basis of reserves so as to improve the development effects of gas reservoirs continuously.
文摘This paper presents two methods for easy determination of water influx in reservoirs based on the material balance theory of reservoirs,i.e.,the Net Production Volume Curve,and the Production Index Curve.These methods can be used for esti-ma tion of water influx in reservoirs without any assumption of aquifer shape and size by applying the production performance data.Hence the tedium of the c onventional trial-and-error calculations and obvious uncertainty could be over come in ap plication of the easy and practical new methods.
