Reservoirs are usually exposed to sediment accumulation problems that will lead to reduction in their storage capacity. This problem directly affects the performance of the dams and causes shortage of their useful lif...Reservoirs are usually exposed to sediment accumulation problems that will lead to reduction in their storage capacity. This problem directly affects the performance of the dams and causes shortage of their useful life. The simplest technique to estimate sediment deposition rate is using sediment rating curve with sediment trapping efficiency (TE) of the reservoir. Many empirical and semi-empirical approaches have been suggested for to determine this term depending on the annual inflow rate, reservoir characteristics and features of the catchments area. In this study six different empirical methods depending on the residence time principle (water retention time) were used. These approaches were reviewed and applied to determine TE of Mosul dam reservoir (MDR) for period 1986 to 2011. The monthly operating data for inflow, outflow and water elevations for MDR were used to determine monthly TE and long-term TE for whole period of MDR using the mentioned methods. Furthermore, the monthly inflow rate for River Tigris upstream MDR, its sediment rating curve and sediment feeding from valleys around MDR were used to estimate the amount sediment coming to the reservoir. The results provided by these methods for TE with sediment coming to MDR were used to compute the amount of sediment deposited in MDR on monthly bases during this period. The results obtained were evaluated using observed bathymetric survey data that had been collected in 2011 after 25 years of the operation of the dam. The results showed all the mentioned methods gave convergent results and they were very close to bathymetric survey results for estimating the volume of sediment deposited especially that proposed by Ward which gave 0.368% percentage error. Furthermore, the result computed using monthly TE gave good agreement if compared with that long-term TE where the percentage error was ranging between –3.229% to 1.674% for monthly adopted data and –4.862% to?–2.477% for whole period data. It is believed that this work will help others to use this procedure on other reservoirs.展开更多
This article analyses the procedure of exploration of the Tertiary subtle trap in Jiyang depression and divides the Tertiary subtle trap into 3 types (lithologic reservoir, stratigraphic reservoir and fractured reserv...This article analyses the procedure of exploration of the Tertiary subtle trap in Jiyang depression and divides the Tertiary subtle trap into 3 types (lithologic reservoir, stratigraphic reservoir and fractured reservoir) and 8 groups, then summarizes the common feature and founding discipline of the subtle trap and finds 4 accumulating modes including steep slope mode, depression mode, center anticline mode and gentle slope mode. Its main exploration methods are explicated from the viewpoint of reservoir geological modeling, description of recognizing traps and comprehensive evaluation of reservoir and so on.展开更多
Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into th...Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into three types as the Naxi, Tahe and Renqiu ones, increasing successively in the development degree of karstificated pores and fissures and the connection degree of independent reservoirs. In these reservoirs, the unity in the fluid feature, pressure and oil-gas-water interface also increases successively from the Naxi to the Renqiu type. The main body of Ordovician reservoirs of the Tahe Oilfield in the Tarim Basin is a network pool rather than a stratified, massive, stratigraphically-unconformed or weathering-crust one. The fluid nature of oil, gas and water, the interface positions and the pressures, as well as the dynamic conditions of fluids within the reservoirs during the production are all different from those in stratified or massive oil and gas reservoirs. Carbonates in the Akekule uplift and the Tahe Oilfield are assemblages of various types of reservoirs, which have an overall oil-bearing potential and obvious uneven distribution. Testing and producing tests are the major means to evaluate this type of reservoirs and acid fracturing improvement is a key link in petroleum exploration and development.展开更多
The foreland basin in West Sichuan is a tectonic unit that has undergone multi-periods tectonic movements of Indosinian-Yanshanian-Himalayan. Since late Triassic, it has been in a passive subsidence environment contro...The foreland basin in West Sichuan is a tectonic unit that has undergone multi-periods tectonic movements of Indosinian-Yanshanian-Himalayan. Since late Triassic, it has been in a passive subsidence environment controlled by basin margin mountain systems and by the compression with abundant sediment sources. With the complex geologic setting, the main geologic characteristics of natural gas reservoir are listed as following： （1） Source rocks are coal-bearing mud and shale series with high to over maturity, and long and progressive hydrocarbon generation-displacement period. The key accumulation period is middle-late Yanshanian epoch. （2） There are three gas-bearing systems vertically, each of which has different reservoir mechanism, main-controlled factors and distribution law, so the exploration thoughts and techniques are also different. （3） Undergoing multi-period generation-migration-accumulation, oil and gas have encountered multi-period modification or destruction, and gas accumulation overpass multiple tectonic periods. So the trap type is complicated and dominated by combination traps. Because the main accumulation period of natural gas is early and the reservoir encountered the modification of strong Himalayan movement, there is great difference in the fullness degree of gas reservoirs and complicated gas-water relation. （4） Reservoir is tight to very tight, but reservoirs of relatively high quality developed under the super tight setting. （5） The key techniques for oil and gas exploration in west Sichuan foreland basin are the prediction of relatively favorable reservoirs, fractures and gas bearing; and the key techniques for oil and gas development are how to improve the penetration rate, reservoir protection and modification.展开更多
At the initial stage of subtle reservoir exploration in the shallow to medium formations of the Taibei Sag, Tuha Basin, so far, three kinds of subtle reservoirs (stratigraphic, lithologic and structural-lithologic res...At the initial stage of subtle reservoir exploration in the shallow to medium formations of the Taibei Sag, Tuha Basin, so far, three kinds of subtle reservoirs (stratigraphic, lithologic and structural-lithologic reservoirs) have been found. Since both the amount and reserve of the discovered subtle reservoirs are small, a great exploration potential remains in the Taibei Sag. The shallow to medium formations in the west of the Taibei Sag were divided into three second-order sequences and ten third-order sequences, of which the rising cyclothems of SQ(J2q) and SQ8 (J2s2) datum level are major exploration targets for the subtle reservoirs (lithologic). The depositional systems of Qiquanhu and Subashi braided river delta were developed there, where the sedimentary sand body is dominated by the regional slopes and slope break belts. There are four main modes the formation of lithologic traps: deltaic front onlap on the slope belt, deltaic front toplap on the slope break belt, lately tilted frontal sand body and sublacustrine fan—slope fan on the slope break belt, of which the first three modes are the major styles of the formation of subtle reservoirs. Major targets for subtle reservoir exploration in the near future include Putaogou Member on the north slope of Huoyanshan, the east slope of Pubei, the nose-like palaeohigh regions of Huobei, Subashi and Lianmuqin, around the Shengbei secondary sag.展开更多
文摘Reservoirs are usually exposed to sediment accumulation problems that will lead to reduction in their storage capacity. This problem directly affects the performance of the dams and causes shortage of their useful life. The simplest technique to estimate sediment deposition rate is using sediment rating curve with sediment trapping efficiency (TE) of the reservoir. Many empirical and semi-empirical approaches have been suggested for to determine this term depending on the annual inflow rate, reservoir characteristics and features of the catchments area. In this study six different empirical methods depending on the residence time principle (water retention time) were used. These approaches were reviewed and applied to determine TE of Mosul dam reservoir (MDR) for period 1986 to 2011. The monthly operating data for inflow, outflow and water elevations for MDR were used to determine monthly TE and long-term TE for whole period of MDR using the mentioned methods. Furthermore, the monthly inflow rate for River Tigris upstream MDR, its sediment rating curve and sediment feeding from valleys around MDR were used to estimate the amount sediment coming to the reservoir. The results provided by these methods for TE with sediment coming to MDR were used to compute the amount of sediment deposited in MDR on monthly bases during this period. The results obtained were evaluated using observed bathymetric survey data that had been collected in 2011 after 25 years of the operation of the dam. The results showed all the mentioned methods gave convergent results and they were very close to bathymetric survey results for estimating the volume of sediment deposited especially that proposed by Ward which gave 0.368% percentage error. Furthermore, the result computed using monthly TE gave good agreement if compared with that long-term TE where the percentage error was ranging between –3.229% to 1.674% for monthly adopted data and –4.862% to?–2.477% for whole period data. It is believed that this work will help others to use this procedure on other reservoirs.
文摘This article analyses the procedure of exploration of the Tertiary subtle trap in Jiyang depression and divides the Tertiary subtle trap into 3 types (lithologic reservoir, stratigraphic reservoir and fractured reservoir) and 8 groups, then summarizes the common feature and founding discipline of the subtle trap and finds 4 accumulating modes including steep slope mode, depression mode, center anticline mode and gentle slope mode. Its main exploration methods are explicated from the viewpoint of reservoir geological modeling, description of recognizing traps and comprehensive evaluation of reservoir and so on.
文摘Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into three types as the Naxi, Tahe and Renqiu ones, increasing successively in the development degree of karstificated pores and fissures and the connection degree of independent reservoirs. In these reservoirs, the unity in the fluid feature, pressure and oil-gas-water interface also increases successively from the Naxi to the Renqiu type. The main body of Ordovician reservoirs of the Tahe Oilfield in the Tarim Basin is a network pool rather than a stratified, massive, stratigraphically-unconformed or weathering-crust one. The fluid nature of oil, gas and water, the interface positions and the pressures, as well as the dynamic conditions of fluids within the reservoirs during the production are all different from those in stratified or massive oil and gas reservoirs. Carbonates in the Akekule uplift and the Tahe Oilfield are assemblages of various types of reservoirs, which have an overall oil-bearing potential and obvious uneven distribution. Testing and producing tests are the major means to evaluate this type of reservoirs and acid fracturing improvement is a key link in petroleum exploration and development.
基金These research results are part of two key national science and technology projects carried out in the period of"ninth-five to tenth-five"(No.96-110-03-01 and 2004BA16A05)financially supported by the Ministry of Science and Technology of the People's Republic of China
文摘The foreland basin in West Sichuan is a tectonic unit that has undergone multi-periods tectonic movements of Indosinian-Yanshanian-Himalayan. Since late Triassic, it has been in a passive subsidence environment controlled by basin margin mountain systems and by the compression with abundant sediment sources. With the complex geologic setting, the main geologic characteristics of natural gas reservoir are listed as following： （1） Source rocks are coal-bearing mud and shale series with high to over maturity, and long and progressive hydrocarbon generation-displacement period. The key accumulation period is middle-late Yanshanian epoch. （2） There are three gas-bearing systems vertically, each of which has different reservoir mechanism, main-controlled factors and distribution law, so the exploration thoughts and techniques are also different. （3） Undergoing multi-period generation-migration-accumulation, oil and gas have encountered multi-period modification or destruction, and gas accumulation overpass multiple tectonic periods. So the trap type is complicated and dominated by combination traps. Because the main accumulation period of natural gas is early and the reservoir encountered the modification of strong Himalayan movement, there is great difference in the fullness degree of gas reservoirs and complicated gas-water relation. （4） Reservoir is tight to very tight, but reservoirs of relatively high quality developed under the super tight setting. （5） The key techniques for oil and gas exploration in west Sichuan foreland basin are the prediction of relatively favorable reservoirs, fractures and gas bearing; and the key techniques for oil and gas development are how to improve the penetration rate, reservoir protection and modification.
文摘At the initial stage of subtle reservoir exploration in the shallow to medium formations of the Taibei Sag, Tuha Basin, so far, three kinds of subtle reservoirs (stratigraphic, lithologic and structural-lithologic reservoirs) have been found. Since both the amount and reserve of the discovered subtle reservoirs are small, a great exploration potential remains in the Taibei Sag. The shallow to medium formations in the west of the Taibei Sag were divided into three second-order sequences and ten third-order sequences, of which the rising cyclothems of SQ(J2q) and SQ8 (J2s2) datum level are major exploration targets for the subtle reservoirs (lithologic). The depositional systems of Qiquanhu and Subashi braided river delta were developed there, where the sedimentary sand body is dominated by the regional slopes and slope break belts. There are four main modes the formation of lithologic traps: deltaic front onlap on the slope belt, deltaic front toplap on the slope break belt, lately tilted frontal sand body and sublacustrine fan—slope fan on the slope break belt, of which the first three modes are the major styles of the formation of subtle reservoirs. Major targets for subtle reservoir exploration in the near future include Putaogou Member on the north slope of Huoyanshan, the east slope of Pubei, the nose-like palaeohigh regions of Huobei, Subashi and Lianmuqin, around the Shengbei secondary sag.
