Lithologic Reservoirs

The exploration and development of glutenite reservoir in the steep slope zone of fault basin in eastern China becomes more and more important, but the studies on the physical property evolution and influencing factors are relatively weak, which restricts the further exploration of oil and gas. Taking Paleogene glutenite in northern steep slope zone of Dongying Sag as an example, this paper used physical property data from 22 cored wells to obtain the evolution curve of porosity. Based on the data of thin slice, formation water, physical properties and grading analysis,the influencing factors such as formation water salinity, carbonate content, grain diameter and sorting coefficient etc, were analyzed from the aspects of diagenesis and sedimentation, which affects pore evolution of glutenite reservoir. It is found that cementation and dissolution are different in vertical zone, and the features of pore evolution are mainly affected and controlled by the character of formation water. The model of physical property evolution of glutenite in vertical was established. The result is very important for forecasting favorable reservoir and judging diagenetic environment.

Origin and research methods of lacustrine dolomite

Huang Chenggang,Yuan Jianying,Wu Liangyu,Zhang Xiaojun,Wu Lirong,Pan Xing

2016, Vol.28(2): 7–15 Abstract ( 509 ) PDF (1620 KB) ( 949 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.002

With the deepening of the degree of oil and gas exploration, the dense carbonate exploration field developed near the sedimentary center of lake basin has attracted more and more attention. Through the review of many previous research results, it was found that the research of lacustrine carbonate diagenesis has gotten remarkable achievements in many fields, especially dolomitization which formed high quality reservoir in recent years, including the following aspects：（1） lacustrine carbonate deposition in China has the characteristics of long time span and wide distribution, including Permian, Jurassic, Cretaceous and Paleogene, and it distributed in the sag and slope zone of Junggar Basin, Santanghu Basin, Sichuan Basin and Qaidam Basin; （2） from the physical properties and lithology of reservoir about lacustrine carbonate in China, it is found that the dolomite and dolomitization rock in saline lacustrine developed often associated with shale symbiotic with the characteristic of medium porosity and ultra-low permeability, and the pore types are mainly dolomite intergranular pores; （3） the dolomitization models of lacustrine carbonate mainly include primary biogenic model, penecontemporaneous metasomatism model, hydrothermal metasomatism model and primary dolomitization model related to exhalative hydrothermal activities; （4）the geochemical analysis technologies about major and trace elements, carbon and oxygen isotope and strontium isotope were widely used in the research of lacustrine dolomite, and good results have been achieved.

Characteristics and controlling factors of shale pore structure of Yanchang Formation in Ordos Basin

Xiong Jian,Luo Danxu,Liu Xiangjun,Liang Lixi

2016, Vol.28(2): 16–23 Abstract ( 535 ) PDF (1126 KB) ( 384 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.003

The pore structure characteristics and influence factors of Chang 7 member of shale of the Upper Triassic Yanchang Formation in Ordos Basin were analyzed by low-pressure N2 adsorption/desorption analysis. The result shows that the shale pore structure of Chang 7 member in Ordos Basin is complicated, and pores are mainly consist of parallel-plate pores with four sides open and ink bottle-shaped. The mineral compositions of the shale are mainly quartz and clays, the former content is between 17.1% and 72.33%, and the latter content is between 12.37% and 61.55%. The BJH pore volume of the shale is concentrated in the range of 0.696-6.575 mm3/g, and the BET specific surface area is between 0.380 m2/g and 3.030 m2/g. The contents of TOC, clays and quartz have significant effects on the pore volume and pore specific surface area, whereas the carbonate and feldspar have a little influence. The pore volume and pore specific surface area are positively correlated with the contents of TOC, clays and feldspar, and negatively correlated with the contents of quartz and carbonate. The TOC and clays have significant control on micropore and mesopore volumes, whereas the quartz has positive effect on macropore volumes.

Characteristics of micropores and diagenesis of tight sandstone reservoirs: A case study from the fifth member of Xujiahe Formation in Xinchang area, western Sichuan Depression

Huang Jing,Li Qi,Kang Yuanxin,Liu Yong,Xiong Liang,Li Huaji

2016, Vol.28(2): 24–32 Abstract ( 436 ) PDF (2091 KB) ( 332 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.004

In order to find out effective reservoirs in Xinchang area, western Sichuan Basin, the data of rock slices, casting slices, scanning electronic microscope and micro-CT scanning, as well as reservoir physical properties, were used to discuss the characteristics of petrologic features, reservoir spaces, pore types and diagenesis of tight sandstone reservoir of the fifth member of Xujiahe Formation. The results show that the tight sandstone is mainly of lithic sandstone and lithic quartz sandstone. The porosity of the reservoir is low and the reservoir is super tight. Reservoir space consists of nano intergranular pores, micron dissolved pores and micro cracks of different genesis, among which the intergranular pores are the main reservoir space. According to the micro-CT scanning results, the abundance of organic matter in the sandstone controls the development and distribution of pores, and the porosity increases with the raise of the abundance of organic matter. The shape and distribution of micro pores affect reservoir connectivity, and the connectivity rate of concentrated micro pores is superior to scattered micro pores. Compaction, replacement and cementation are the major causes of density of reservoir. Dissolution has a certain positive impact on improving the physical properties of reservoir, but makes little change of porosity.

Gas exploration prospects of the Upper Paleozoic in Tongxu area,southern North China Basin

Wang Fubin,Ma Chao,An Chuan

2016, Vol.28(2): 33–40 Abstract ( 439 ) PDF (2443 KB) ( 326 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.005

The Carboniferous and Permian strata in Tongxu area of southern North China Basin are relatively complete preserved. The natural gas reservoir conditions are similar to those of the Ordos Basin. Based on the theory of tight sandstone gas reservoir forming in Ordos Basin, the basic petroleum geological conditions and the relationship between trap formation period and gas migration and accumulation period of the Upper Paleozoic were analyzed, then the gas exploration prospects of this area can be explicit. The research shows that the coal of Carboniferous and Permian in Tongxu area is well developed, the average organic carbon content of coal is 62.9%, the average maturity of organic matter is 3.34%, and the organic matter of coal belongs to Ⅱ2 type, which is a good regional source rock. Reservoir rocks mainly distributed in a large area of delta plain distributary channel sandstone, and average porosity is 2.7%, the average permeability is 2.25 mD, and intergranular pore and intergranular dissolved pore are developed. Mudstone of Upper and Lower Shihezi Formation is developed. The breakthrough pressure of mudstone saturated with gas is 5.88-9.80 MPa, and it is a good regional cap rock. The tight sandstone lithologic trap is the most favorable trap type, and it formed before the hydrocarbon generation, and the matching relationship is good. The central and southern area of the Weibei Slope is favorable for the development of tight sandstone lithologic gas reservoir.

Impacts of CO₂ on fluid density during the evolution of organic material of coal series

Fu Deliang,Zhou Shixin,Ma Yu,Li Jing,Li Yuanju

2016, Vol.28(2): 41–46 Abstract ( 359 ) PDF (1537 KB) ( 470 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.006

By the pressurized sealed gold tube pyrolysis experiments, the fluid composition of Jurassic coal series from Minhe Basin at different maturity was obtained, the fluid density was calculated by PR state equation in software PVT-sim, and the impact of CO2 from the evolution of coal on fluid density was discussed particularly. The result shows that the fluid density of coal generated hydrocarbon decreases with the increasing of maturity. At 10-50 MPa, 25-125 ℃ and EASY%Ro at 0.86%-2.52%, the density of liquid phase and the vapor phase was 0.51-0.85 g/cm3 and 0.05-0.85 g/cm3 respectively. Large quantity of CO2 would generate during the evolution of the coal, which will impact the petroleum density directly. In this study, the density of liquid and vapor fluid both increases with the increasing of CO2 content. The density was changed with the change of deviation factor and average molecular weight. At low maturity stage, with the increasing of CO2 content, the density was increasing mainly because of the decreasing of deviation factor（Z）. At high maturity stage, with the increasing of CO2 content, the density was increasing mainly because of the increasing of average molecular weight.

Pore structure characteristics of Jurassic Toutunhe Formation in eastern slope of Fukang Depression, Junggar Basin

Ji Hongjie,Li Xiaoyan,Tao Huifei,Wang Qi,Wu Tao，Su Long

2016, Vol.28(2): 47–55 Abstract ( 485 ) PDF (2433 KB) ( 336 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.007

Petrologic characteristics, physical properties and pore structure characteristics of Toutunhe Formation in eastern Fukang slope were studied using casting thin section observation, scanning electron microscope analysis, mercury injection test. The results show that the lithology of Toutunhe Formation is dominated by feldspar lithic sandstone and lithic sandstone with the characteristics of low compositional maturity and medium-high textural maturity; physical properties is well and the medium permeability reservoirs have a higher proportion; the main types of pores in this zone are intergranular pore and feldspar dissolved pore, while the types of throat are mainly narrow neck shape and sheet shape; pore structure has the characteristics of medium-small pore throats, poor sorting and well pore throat connectivity. Besides, by means of nonlinear canonical correlation analysis among characteristic parameters of microscopic pore structure and macroscopic physical properties, the classification parameters of pore structure were picked out. The methods of data configuration and mathematical statistics were used to establish classification standard of pore structure. The reservoir pore structure of Toutunhe Formation is classified into four types on the basis of this classification standard: macro-medium pore and coarse throat structure （typeⅠ）, medium pore and medium throat structure（typeⅡ）, mediumsmall pore and fine throat structure （typeⅢ） and small-micro pore and micro throat structure （typeⅣ）.

Characteristics of source-reservoir-caprock assemblage and hydrocarbon accumulation of Yanchang Formation in Binchang block, Ordos Basin

Chen Hehe,Zhu Xiaomin,Chen Chunfang,Yin Wei

2016, Vol.28(2): 56–63 Abstract ( 545 ) PDF (3963 KB) ( 617 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.008

Based on the data of geochemistry, cores, logs and oil test, this paper analyzed the characteristics of sourcereservoir-caprock assemblage and hydrocarbon accumulation of Yanchang Formation in Binchang block, Ordos Basin. The result shows that the Zhangjiatan shale at the bottom of Chang 7 oil reservoir is hydrocarbon source rock of Yanchang Formation in Binchang block. The sand bodies of delta front underwater distributary channel and gravity flow in Chang 8 to Chang 6 oil reservoir set act as reservoir. The dark mudstone of semi deep-deep lake facies in Chang 9 to Chang 4+5 oil reservoir set act as caprock. Four sets of source-reservoir-caprock assemblages were divided: （1） Chang 7 as source, Chang 91 as reservoir and upper Chang 9 as caprock; （2） Chang 7 as source, Chang 81 as reservoir and Chang 7 as caprock; （3） Chang 7 as source, Chang 72 as reservoir and upper Chang 7 as caprock; （4） Chang 7 as source, Chang 63 as reservoir and Chang 6-Chang 4 as caprock. According to the configuration relationship between source and reservoir and the stacking patterns of source, reservoir and cap, the source-reservoir-caprock assemblage can be divided into successive type （2 and 3） and discontinuous type （1 and 4）. The successive type of assemblage is controlled by the distribution of Zhangjiatan shale, reservoirs quality and the development degree of fault-fracture system. The discontinuous type of assemblage is controlled by the oil source, faults, the distance between source and reservoir as well as the distribution of favorable reservoirs. Successive type of assemblage has advantages in hydrocarbon injection, seal quality and higher oil saturation compared to discontinuous type assemblage.

Effect of karst paleogeomorphology of Ordovician on gas-water distribution of Ma 5₄¹ in Wushenqi-Zhidan area

Wang Yang,Li Shutong,Mou Weiwei,Shi Yunhe,Nie Wancai,Yan Cancan

2016, Vol.28(2): 64–71 Abstract ( 505 ) PDF (3226 KB) ( 646 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.009

Karst paleogeomorphology of Ordovician controls gas-water distribution in Wushenqi-Zhidan area of Ordos Basin. Based on the regional tectonic setting and stratigraphic distribution, the compensation thickness impression method （the stratum thickness from the Maoergou limestone to the bottom of Benxi Formation） was used to rebuild the karst paleogeomorphology of Ordovician which includes three types of second-order paleogeomorphology and five types of third-order paleogeomorphology in wushenqi-zhidan area. The three types of second-order paleogeomorphology include karst highland, karst slope and karst basin, and the five types of third-order paleogeomorphology include tableland, shallow depression, monadnock, groove and depression. Overall, the karst highland mainly located in the Wushenqi-Wuqi area, most of the central part of the study area like the east of the Wushenqi-Jianbian-Zhidan belongs to karst slope, and the east of the Hengshan-ansai area pertains to karst basin. Through the analysis of gas reservoir profile and the superposition of karst paleogeomorphology and gas-water distribution, it is found that the water in the study area is mainly distributed in the karst highland, while the gas is mainly distributed in the karst slope or the karst monadnock. In conclusion, although karst highland has a good reservoir space, because of the late tectonic inversion, the re-differentiation and migration of the gas and water lead to relatively enriched groundwater. However, karst slope is located in the transitional zone between karst highland and karst basin and contains a large number of the soluble minerals. It formed well developed reservoir space like pores, vugs and fractures because it has experienced the strong gypsum-dissolving process and the weak cementation. Therefore, it is the most favorable gas accumulating paleogeomorphology unit, followed by karst highland, karst basin worst. In addition, karst monadnock and the contact zone between karst highland and karst slope also have a good natural gas accumulation condition.

Estimation of denudation thickness of Mesozoic strata and paleostructure restoration in Zhenjing area, Ordos Basin

Li Chao,Zhang Liqiang,Zhang Likuan,Wang Peng,Hu Caizhi,Zhang Haisen

2016, Vol.28(2): 72–80 Abstract ( 440 ) PDF (3356 KB) ( 370 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.010

The Mesozoic and the overlain strata in Zhenjing area underwent four stages of formation uplift and denudation events corresponding to the unconformity surfaces of Jurassic-Triassic, Jurassic Yanan Formation-Zhiluo Formation, Jurassic-Cretaceous and Cretaceous-Quaternary. Compaction curve extrapolation method and formation tendency correlation method were used to estimate the denudation thickness resulted by the four stages of tectonic uplift events from Triassic, and the denudation thicknesses from different stages were compared. Basin numerical modeling method was applied to restore the structural evolution process of the top surface of Chang 8 oil reservoir set. The result shows that the strata denudation thickness of the end of Triassic Yanchang Formation is 345-465 m, the strata denudation thickness of the end of Middle Jurassic Yan’an Formation changes from 150 m to 220 m, and the strata denudation thickness of the end of Jurassic Anding Formation is 160-250 m. However, the denudation thickness of the end of Late Cretaceous-Neogene Zhidan group is much more than that of the other three stages, and it varies from 980 m to 1 280 m. The structural form of Yanchang Formation in the study area was controlled by tectonic subsidence and uplift and denudation, with tilting structural evolution process from Triassic.

Sedimentary environment of Lower Triassic Baikouquan Formation in Mahu Sag, Junggar Basin: A case study from Ma 18 well

Li Xing， Zhang Liqiang， Shi Hui， Zheng Yiding

2016, Vol.28(2): 80–85 Abstract ( 443 ) PDF (998 KB) ( 358 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.011

The ancient sedimentary environment of clastic rock directly controls the type, distribution and evolution of sedimentary facies, which affects the distribution of high quality reservoir and favorable oil and gas area. The geochemical characteristics of element were used to analyze the sedimentary environment of clastic rock reservoir, and portable X-ray fluorescence （XRF） tester was applied to systematically test the contents of more than 40 elements from 415 groups of samples of Lower Triassic Baikouquan Formation in Ma 18 well in Mahu Sag in the northwestern margin of Junggar Basin. The geochemical characteristics of elements and the changing trend of paleoclimate, paleosalinity and oxidation-reduction states of the sedimentary environment were analyzed. The results show that element content and ratio have certain fluctuations from bottom to top, while in overall, it was formed in the warm and humid, freshwater, brackish water, weak layering and oxidizing environment. In addition, from T1b1 to T1b3 , the water temperature, humidity and salinity all have a tendency to increase, and the Si/Al ratio has a certain positive correlation with oil saturation.

Characteristics of fluid potential and its implication to hydrocarbon migration and accumulation in block A, Lower Congo Basin

Cheng Han， Hu Wangshui， Li Tao， Hao Jianrong， Zhao Hongyan3

2016, Vol.28(2): 86–72 Abstract ( 359 ) PDF (1940 KB) ( 356 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.012

Petroleum systems of block A in Lower Congo Basin were divided into two salt layers such as pre-salt and pos-salt, and hydrocarbon of this two systems migrated in different ways. Based on seismic and basin modeling data, temperature and pressure fields were employed to calculate density of oil and gas in order to find out the characteristics of fluid potential and its implication to hydrocarbon migration and accumulation in block A of Lower Congo Basin. The fluid potential of post-salt petroleum system was controlled by depth and sedimentary facies. Hydrocarbon migration dynamics exhibited fluid potential driving difference, with the most important controlling factors being buoyancy and capillary pressure. The key factor of hydrocarbon accumulation is the good match between effective tensional fault, marine oil-gas source rock and turbidite stone. The fluid potential of pre-salt petroleum system was characterized by depth-controlled and hydraulic pressure-controlled while buoyancy and overpressure allowed hydrocarbons to migrate. The key factor of hydrocarbon accumulation is the coupling between burial depth of strata underlying salt layer and salt thickness. Overall, fluid potential is better matched with hydrocarbon discovery in the study area, and the coinciding lower regions of oil, gas and water potential are the major next-term exploration area.

Integrated evaluation method of water flooded layer in ultra-low permeability reservoir in peripheral Daqing Oilfield

Zhang Meiling， Qi Meng， Lin Lili2

2016, Vol.28(2): 93–100 Abstract ( 390 ) PDF (618 KB) ( 346 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.013

Affected by the internal complex pore structure of low permeability reservoir, the reflecting ability of logging value to the changes of fluid in the formation is weak. Thus, it is difficult to use logging data to distinguish water flooded degree of reservoir. It can reflect the current water flooded degree of sand body by using dynamic information which is from interconnected sand body between injection wells and production wells during the water injection development process. The implementation steps are as following: （1） study the variation characteristics of logging value of flooded layers by using basic principle of logging methods, give the identification rules of water flooded degree, and divide the layers which satisfies these rules to uncertain flooded layers; （2） on the basis of building dynamic development unit, carry out further determination for the water flooded degree of the uncertain flooded layers according to the water absorbing capacity of small layers and water content of separate layer during the fluid production process from in adjacent wells. These two steps were applied to identify water flooded degree in ultra-low permeability oilfield in peripheral Daqing Oilfield, and good application effect was obtained.

A method of judging lateral sealing of fault by mudstone content of fault rock and its application

Fu Guang,Xu Bilin,Li Na

2016, Vol.28(2): 101–106 Abstract ( 399 ) PDF (1558 KB) ( 419 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.014

In order to judge lateral sealing of fault more easily, based on the study of lateral sealing mechanism of fault and its influencing factors, minimum value of mudstone content required in lateral sealing of fault was forecast through comparing displacement pressure of fault rock and sealed reservoir. A method for judging lateral sealing ability of fault by using mudstone content of fault rock was established, and it was applied to judge the lateral sealing of No.1-7 reservoirs in lower Ed3 of f-np5-2 fault in No. 5 structure of Nanpu Depression. The result indicates that mudstone content of fault rock in No. 1, 2, 3 and 6 reservoirs in lower Ed3 of f-np5-2 fault is more than the minimum value of mudstone content of fault rock required in lateral sealing of fault. The faults are sealed laterally, which is favorable for oil and gas accumulation, so drilling shows oil layer. Mudstone content of fault rock in No. 4, 5 and 7 reservoirs in lower Ed3 of f-np5-2 fault is less than the minimum value of mudstone content of fault rock required in lateral sealing of fault. The faults are unsealed laterally, which is unfavorable for oil and gas accumulation, so drilling shows water layer. The judging result accords with oil and gas distribution in lower Ed3 of NP503 well currently, which indicates that the method is feasible to judge lateral sealing of fault.

Influence of velocity changing of gas reservoir and seal on seismic response and AVO type

Han Guangming,Pan Guangchao,Fu Chen,Luo Qi,Shao Yuan,Wang Rui

2016, Vol.28(2): 107–113 Abstract ( 484 ) PDF (2093 KB) ( 393 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.015

Some gas layers with abnormal seismic response characteristics were found in recent years in the Yinggehai Basin. By means of studying the P-wave velocity changing of gas reservoir and seal, the reasons of the new type of seismic response characteristics formed in gas reservoir were analyzed. Compared with the normal seismic response characteristic of “two red with one black” of gas reservoir, the new type of seismic response characteristics of “upper black down red” and “upper red down black” made the seismic response type of gas reservoir richer, which broadens the thought for finding the potential target. In addition, the study of logging rock physics shows that the P-wave and S-wave velocity changing of seal may have the relationship with the AVO type of gas reservoir, and different P-wave and S-wave velocity curve shape corresponds to different AVO type. So we can roughly distinguish the AVO type according to the P-wave velocity, S-wave velocity and P-wave impedance curve shape in the prestack AVO study.

Quantitative lithology identification technology of complex sand-conglomerate bodies#br#

Wu Zhaohui,Xu Shouyu,Liu Xilei,Wu Yinghao,Song Honglin,Niu Lijuan

2016, Vol.28(2): 114–118 Abstract ( 446 ) PDF (2206 KB) ( 308 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.016

The lithologies of complex sand-conglomerate bodies are various, and effective lithology identification method is still lacked. Through comparing many lithologies and well logging data, a new quantitative lithology identification technology was formed. Near source sand-conglomerate bodies in CH Oilfield were taken as the study case. Firstly, some lithologies were accurately identified with cores, grain size and cast slice data, and the critical log values of key lithologies were determined based on cross plots. Secondly, sandstone, conglomerate, and sandy conglomerate were identified with the array induction log curve. Thirdly, sandstone, conglomerate, muddy sandstone and muddy conglomerate were further identified with the density log curve. Finally, limy sandstone and limy conglomerate were identified with the critical values of three-porosity curves （DEN, AC, CNL） and wave impedance log curve, and altogether 7 kinds of lithologies were identified in complex sand-conglomerate bodies. Judging from the results, the correct rate is more than 75%.

Low salinity waterflooding to enhance oil recovery of carbonate reservoirs

Li Haitao,Li Ying,Li Yahui,Wang Ke

2016, Vol.28(2): 119–126 Abstract ( 482 ) PDF (1287 KB) ( 438 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.017

For carbonate reservoirs, it is common that oil recovery is relatively low and water cut rises quickly due to the complex underground conditions, such as a wide range of fractures and caves. Low salinity waterflooding is an enhanced oil recovery （EOR） technique with low cost and high effects, and it has been extensively researched since 1990s. The stimulation mechanism, laboratory methods and field operation conditions for low salinity waterflooding of carbonate reservoir were analyzed. Experimental results reveal that wettability alteration and enhancement of connectivity among different pore systems are responsible for the improved recovery. The wettability alteration can be attributed to surface charges alteration or microscopic dissolution of minerals, which is in fact the reaction between main determining ions （SO42-，Ca2+ ，Mg2+ ）and rock surfaces. However, the enhancement of connectivity among different pore systems is caused mainly by microscopic dissolution of minerals. Numerous laboratory methods are applied to obtain the main mechanisms for low salinity waterflooding on carbonate oil reservoirs, such as coreflooding study, imbibition test, interfacial tension measurement, contact-angle measurement, nuclear magnetic resonance technique, ion analysis and Zeta potential measurement. When performing low salinity waterflooding, higher oil recovery will be achieved if ions composition can be optimized. In addition, the combination of low salinity waterflooding and polymer flooding will also remarkably improve oil recovery. In China, there is large number of carbonate reservoirs, therefore, it is of significance to conduct theoretical and applied researches related to low salinity waterflooding.

Influencing factors for temperature field distribution of gas hydrate based on finite element method

Li Bingfan,Pan Zhen,Shang Liyan,Ma Guiyang,Wei Liwa,Ma Peimin

2016, Vol.28(2): 127–132 Abstract ( 386 ) PDF (2280 KB) ( 347 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.02.018

Gas hydrate has became the most promising clean energy in the 21st century, and note hot exploration is considered as the most effective mining method. Taking a permafrost gas hydrate mining area as an example, on the basis of hydrate dissociation kinetics model, this paper established gas hydrate decomposition thermodynamic model based on the finite volume method, and analyzed the influencing factors for temperature field distribution of gas hydrate. The results show that gas hydrate in a high temperature region is gradually increased and the rate of decomposition is accelerated with the gradual increase of water injection rate and unchanged other conditions. With the gradual increase of porosity and water temperature, high-temperature region is basically the same trends. However, the gas temperature will increase in the surface. Note hot exploration was carried out in this mining area, and the hydrate dissociation velocity is fastest with the water injection rate at 6 m/s and water temperature at 80 ℃, with better economic efficiency. This result can provide theoretical guidance for the heat mining practice.