Lithologic Reservoirs

Some quantifying parameters are so far unclear about water cut rising rule of reservoirs. The corresponding relationship between water cut rising features and geological features of reservoirs has not been established. Reservoir geological model and case analyses were used to define the quantifying parameters of water cut rising rate. The quantifying parameters of water flooding rate and the corresponding relationship between water breakthrough time in wells and bottom-water types were obtained. Two types of reservoir heterogeneity were defined: discrete heterogeneity and continuous heterogeneity.Discreteheterogeneousreservoirshavethestep-typecurveof water cut rising, while continuous heterogeneous reservoirs have the continuous curve of water cut rising. The relative permeability curves of porous media are not straight lines because of high capillary pressure, which results in the non-straight line type of water cut rising curves in such reservoirs. However, the relative permeability curves of fractured-vuggy media are straight lines because of low capillary pressure, which results in the straight line type of water cut rising curves in fractured-vuggy reservoirs.

Research progress of CO₂ flooding and geological storage in gas reservoirs

Guo Ping,Xu Qinghua,Sun Zhen,Du Jianfen,Wang Zhouhua

2016, Vol.28(3): 6–11 Abstract ( 475 ) PDF (401 KB) ( 706 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.002

Nowadays, with the increase of CO2 emissions, the global greenhouse effect has become increasingly significant, so the disposal of CO2 become more and more important. While in China all of the projects of CO2 storage are conducted in oil reservoir or saline formation, there is no project of CO2 flooding plus CO2 capture and storage （CCS）in gas reservoirs and little studies about it. By reviewing a large number of studies about this topic, and the existing projects of CO2 flooding and geological storage projects of depleted gas reservoirs, as well as CO2 flooding simulation studies, this paper analyzed the affecting factors, the advantages and disadvantages of enhanced gas recovery （EGR）by CO2 flooding in gas reservoirs, and pointed out that the works should be done when applying it to tight gas reservoirs. The result shows that CO2 storage in depleted gas reservoirs is reliable, with large storage capacity and low cost, and has some additional economic benefits. Irreducible water can reduce the impact of heterogeneity on EGR. Comparing with the results of gaseous CO2 flooding in moderate or high permeability gas reservoirs, the effect of liquid or supercritical CO2 flooding is better. Moreover, the later the start time of CO2 flooding is or the higher the injection pressure and rate is, the higher the gas recovery factor will be.

Main controlling factors of the enrichment of Chang7 tightoil of Yanchang Formationin southern Ganquan area,Ordos Basin

Zhang Fengqi，Zhang Fengbo,Zhong H ongl i，W ang Le,Ji ao Tao,W u Pengbo

2016, Vol.28(3): 12–19 Abstract ( 594 ) PDF (878 KB) ( 604 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.003

Based on the analyses of the main controlling factors for tight oil formation and its relationship with hydrocarbon distribution, the data of well logging, mud logging, well test and production test, laboratory analysis and test were used to study the main controlling factors of the enrichment of Chang 7 tight oil of Yanchang Formation in the southern Ganquan area, Ordos Basin. The results show that source rocks, source-reservoir assemblage, sedimentary facies and physical properties are the main controlling factors of the enrichment of Chang 7 tight oil in Ordos Basin.The widely developed high-quality source rocks in Chang 7 3 subzone are an important foundation for tight oil formation in the middle and upper layer of Chang 7, and control the total depth and scope of tight oil in each layer. Good source-reservoir assemblages ensure that the oil generated from the source rocks in Chang 7 3 subzone can expel and migrateinto the Chang 7 2 reservoir along the contact surfaces of sourcereservoir between Chang 7 3 subzone and Chang 7 2 subzone. Favorable sedimentary facies zones control the distribution of tight oil in Chang 7. The relatively high porosity and high permeability sand bodies sealed by tight sandstone and mudstone control the accumulation of tight oil in Chang 7. This study may play a guiding role for the exploration of Chang 7 tight oil in Ordos Basin.

Characteristics and formation mechanism of Chang6 reservoir in Jiyuanarea

Liu Zhenwang,Zheng Xi，Zhong Zhangqi，Hou Dujie,Liu Minzhao

2016, Vol.28(3): 20–26 Abstract ( 464 ) PDF (1503 KB) ( 477 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.004

The formation mechanism of reservoir in Ordos Basin is very complex. The study on reservoir characteristics and formation mechanism is an effective way to find high-quality reservoirs and cognize oil and gas distribution rule.Based on the analyses of casting sections, intrusive mercury curve and logging data, the features of physical properties,microscopic pore structure and intrusive mercury coefficient of Chang 6 reservoir in Jiyuan area were studied. In term of the evaluation of extra-low permeability reservoir, microscopic pore structure can reflect the reservoir quality more effectively. The intrusive mercury coefficient was introduced, which takes into account five factors, including porosity,maximum intake mercury saturation, median radius, displacement pressure and sorting coefficient. 136 rock samples of Chang 6 reservoir were selected to carry out the mercury injection experiment. According to the characteristics of intrusive mercury coefficient and intrusive mercury curve, the reservoirs are divided into four types which are highquality, good, moderate and poor reservoir. The experiment result shows that the larger the intrusive mercury coefficient is, the higher the well test yield in the corresponding zone will be, indicating a certain rationality of intrusive mercury coefficient for reservoir evaluation. The main controlling factors of Chang 6 reservoir in Jiyuan area include sedimentation, secondary dissolution and overpressure. It is suggested that the chlorite cementation zones, secondary pore zones and overpressure zones of subaqueous distributary sand bodies in delta front are the favorable belts for the development of high-quality reservoirs.

Application of EUR distribution analogous method to tight oil assessment:A case study from Lucaogou Formation in Santanghu Basin

G ou H ongguang 1,2,Zhao Li l i，Li ang G ui bi n 2,SheJi achao 2,Li u Junt i an

2016, Vol.28(3): 27–33 Abstract ( 551 ) PDF (531 KB) ( 339 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.005

Tight oil resource assessment is still in the initial stage in China, and the understandings of the resource scale from different experts are different. The Lucaogou Formation in Santanghu Basin is typical tight oil reservoir,and source rock thickness, maturity and total organic carbon content are the main factors for controlling hydrocarbon enrichment. Combined with practical production, a geological classification evaluation criterion of favorable area was established, and three favorable areas for hydrocarbon exploration were selected. With the key parameters of EUR （ estimated ultimate recovery ） distribution analogous method as the core, the decline law of well production was applied to obtain the EUR value of single well in different evaluation areas. The reasonable well spacing method, delineation drilling test method and microseismic fracture monitoring method were used to study the well control area parameters,and multi-methods were mutually verified to ensure the scientificity and rationality of the evaluation results. The evaluation results have been applied to exploration and production, and effectively guided the oil and gas exploration deployment. This method has important reference for other tight oil region.

Sedimentary characteristics and evolution model of delta in backbulge zone:A case study in Sangtamu area

Tang W u 1,W ang Y i ngm i n 2,Zhong M i hong 3

2016, Vol.28(3): 34–41 Abstract ( 496 ) PDF (1018 KB) ( 365 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.006

Tarim Basin entered into foreland basin evolution stage during Triassic period, forming three typical tectonic units （foredeep, forebulge, and backbulge）. In order to discuss the sedimentary characteristics of deltas in the backbulge zone, based on the comprehensive analyses of cores, logging, analysis assay as well as 3D seismic data, the sedimentary characteristics of Triassic Karamay Formation in Sangtamu area were analyzed. The results show that two types of deltas were developed in the study area, namely braided river delta and meandering river delta, and it changed from the former to the latter vertically. The underlying braided river delta is mainly consisted of coarse sandstone, with well lateral continuity and large thickness, while the overlying meandering river delta is exact opposite. Both deltas mainly developed plain and front subfacies. The plain subfacies of braided river delta is primarily composed of distributary channel, while the subaqueous distributary channel microfacies composes the main part of front subfacies, with mouth bar and distal bar locally developed. The distributary channel, levee and swamp microfacies can be identified in meandering river delta plain subfacies, and its front subfacies is chiefly consisted of subaqueous distributary channel and mouth bar. The delta pattern transformation in the study area is controlled by topographic slope change caused by tectonic activities of foreland basin. The paleoclimate changed from arid-semiarid to humid also played an important role. Finally, based on the origin analysis of deltas, the evolution models of delta in backbulge zone were built.

Hydrothermal activities of Ordovician and its significance for alteration to carbonate reservoirs in Yubei area

Zhu Songbai，W ang H ongfeng 1,W ang Shengj un,Zhou Y an,Zhao Zhengchao,W u Ji ngqi ng

2016, Vol.28(3): 42–47 Abstract ( 494 ) PDF (864 KB) ( 639 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.007

The alterations of deep hydrothermal fluids to carbonate reservoirs have gradually drawn much attention,and have become a new field for hydrocarbon exploration of deep carbonate reservoirs. Based on the analyses of cores, thin sections, cathodoluminescence, SEM, geochemistry and inclusion thermometry, the hydrothermal activities of Ordovician in Yubei area of Tarim basin were studied. The results show that silicification and dissolved pores can be observed in the dolomite of Ordovician, and some drusy quartz and dolomite can be found in pores of the dolomite. Dolomite with wavy extinction, saddle dolomite, as well as barite and pyrite filled in intercrystalline pores also can be seen via thin sections and SEM. Compared with ordinary dolomite, the siliceous dolomite contains relatively enriched Ce and Eu, with high content of Ba, Zn and low content of Sr. The carbon and oxygen isotopic composition of the siliceous dolomite is relatively lower and the ratio of n （ 87 Sr ） to n （ 86 Sr ） is higher than that of the ordinary dolomite, and the homogenization temperature and salinity of fluid inclusions also are relatively high.Combined with the regional basement faults, it is believed that hydrothermal activities exist in Ordovician in this area, and dissolved pores are produced in these events, which means a prospective significance for the exploration of Ordovician deep dolomite.

Quantitative characterization of pore structure in shale reservoir of Longmaxi Formation in Sichuan Basin

GongXiaoping, TangHongming, ZhaoFeng, WangJunjie, XiongHao

2016, Vol.28(3): 48–57 Abstract ( 544 ) PDF (1301 KB) ( 762 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.008

Quantitative characterization of pore structure in shale can indicate some basic parameters for shale reservoir quality evaluation. However, it is difficult to use conventional methods to accurately characterize the micron to nano-scale pore structure in shale. This paper took gas-bearing shale of Longmaxi Formation in Sichuan Basin as a study object to comprehensively compare the principles, advantages and disadvantages of the mostly used test approaches such as nitrogen adsorption, high-pressure mercury injection and nuclear magnetic resonance（NMR）, etc. Nitrogen adsorption method is usually used to test the pore which is 1-50 nm in size, high-pressure mercury injection method is proposed to test for macropore （> 50 nm）, and NMR can reflect the pore size distribution by testing the relaxation time （T2） spectrum of the saturated fluid in shale. The pore size in shale is positively related to the T2 value tested by NMR and there exists a conversion coefficient （C）. A new method of combining NMR with low-pressure nitrogen adsorption for testing pore size distribution in shale was proposed, which optimizes the conversion coefficient （C） between pore size （D） tested by low-pressure nitrogen adsorption method and T2 value tested by NMR method firstly, and then the pore size distribution can be characterized by NMR based on the C value. Large amounts of micron-fractures could be caused in the process of high-pressure mercury injection, and these fractures are considered to be artificial fractures which is difficult to distinguish from natural micro-fractures, so the new method can make up for the deficiency of the conventional method for pore size distribution characterization by combining lowpressure nitrogen adsorption and high-pressure mercury injection. In addition, because of the advantages of simple sample processing, small artificial destruction, no external pressure, etc, it is recommended to characterize the pore structure by combining low-pressure nitrogen adsorption and NMR to reflect the pore throat distribution scientifically and accurately. The result shows that the pore size distribution in Longmaxi shale is bimodal or trimodal, and the main pore size is 0.2-100.0 nm. The mesopore and micropore are predominated, and their volume percents are 67.75% and 25.33% respectively. This method was used to quantitatively characterize the pore structure in shale in the study area, and the test result accords with the pore structure characteristics of Longmaxi shale.

Characteristics and evolution of the Ordovician dolomite reservoir of Ma 5 member in Fuxian area, Ordos Basin

Li Wei，Zhang Juntao 3,Zhu Xiaomin 2,Sun Yipu3,Li Shujun

2016, Vol.28(3): 58–67 Abstract ( 553 ) PDF (1599 KB) ( 526 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.009

There is a set of weathering crust reservoir developed in Majiagou Formation in Ordos Basin. Based on experimental analyses of cores, thin section examination, cathodoluminescence, electronic probe, carbon and oxygen isotope, and physical property, the characteristics and evolution of weathering crust reservoir in Fuxian area were studied. The result shows that gypsum and anhydrite mainly occurred as isolated nodules in Ma 5 penecontem poraneous dolomite in Fuxian area. These nodules were dissolved by meteoric water during Caledonian and experienced other diagenesis after buried, which forms the most significant reservoir spaces with diversiform filling degree and types. Sedimentary facies affects the porosity directly by controlling the size and quantity of nodules,and it could affect the reservoir permeability indirectly as the small quantity of nodules is not beneficial to the development of micro cracks among pores （ Anhydrite would dilate when absorbing water and increase formation pressure, and the pressure would decrease after the nodules were dissolved, which then generated micro cracks ） Reservoir properties are principally determined by epidiagenesis. Gypsum was dissolved by meteoric water and pores formed during that period, and the pores located in the lower part of paleo-landform generally suffered totally filling of calcite. The effect of burial diagenesis on reservoirs in the study area is fairly weaker than that on the samereservoirs in the Central Gas Field of Ordos Basin. The formation mechanism of highquality reservoirs was defined,and it is considered that favorable reservoirs are mainly located in overlapped areas between gypsum-bearingdolomite flat and paleohigh of karst geomorphology. Fine description about sedimentary facies and karst geomor-phology should be the key for the further reservoir prediction.

Origin and controlling factors of calcareous interlayers of Zhujiang Formation in Nanhai A oilfield

Wu Qian，Fang Xiaoyu，Wang Yu，Wu Yukun，Gan Yongnian，Xun Jinlai

2016, Vol.28(3): 68–73 Abstract ( 410 ) PDF (765 KB) ( 477 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.010

Several sets of calcareous interlayers are well developed in Zhujiang Formation in Nanhai A oilfield, and they are the main factors controlling bottom water rising and remaining oil distribution. Based on rock thin section identification, carbon and oxygen isotope analysis, the rock components in calcareous interlayers were studied, and its origin and forming stages were defined. Combined with sedimentary characteristics, the controlling factors of calcareous interlayers were discussed. The results show that calcareous interlayers have consistency at microscopic origin, and they are formed by the chemical precipitation of rock pore fluid during the diagenetic process. The calcareous material came from the crystallization of contemporaneous carbonates, the dissolution of bioclasts and the transformation of clay minerals. The distribution of calcareous interlayers are controlled by structural depth, their thickness ratio to mudstone and sedimentary cycle, with the characteristics of continuity and discontinuity in lateral. The enrichment degree of remaining oil is high in the large distribution area of bottom calcareous interlayers.

Petrophysical facies classification of tight sandstone reservoir and high-quality reservoir prediction: A case study from the second member of Xujiahe Formation in Anyue area, central Sichuan Basin

Chai Yu,Wang Guiwen

2016, Vol.28(3): 74–85 Abstract ( 524 ) PDF (1486 KB) ( 829 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.011

Affectedby geological processes including deposition, diagenesis and tectonism, reservoirs of Xujiahe Formation in central Sichuan Basin are relatively compact with poor physical properties and strong heterogeneity. In order to predict the distribution of high-quality reservoirs and their internal differences of reservoir properties, based on the concept of petrophysical facies, the data of core, thin sections, mercury injection and well logs were utilized to study four controlling factors including lithology and lithofacies, diagenetic facies, fracture facies and pore structure facies of the tight sandstone reservoir of the second member of Xujiahe Formation in Anyue area. Five types of lithology and lithofacies, five types of diagenetic facies, four types of fracture facies and four types of pore structure facies were identified. Well log characterization methods and well-log identification standards were established. Petrophysical facies classification and reservoir quantitative evaluation standard were also put forward. The results show that high-quality reservoirs are mainly located in the favorable superposition of lithology and lithofacies, diagenetic facies,fracture facies and pore structure facies, which is favorable petrophysical facies area. High-quality reservoirs of the second member of Xujiahe Formation are mainly situated in relatively porous and permeable zone in the lower and middle part of the clinoform and fracture-developed zone in the northern part of the study area. The study of petrophysical facies has significant effect on reservoir characterization, high-quality reservoir prediction and evaluation.

Sedimentary characteristics of Lower Cretaceous sublacustrine fan in BN block of BG Basin, Central Africa

Ouyang Xueqi1， Wang Liang2， L iu Feng2， Zheng Rongcai1， Ren Wei1

2016, Vol.28(3): 86–94 Abstract ( 499 ) PDF (1601 KB) ( 462 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.012

Sublacustrine fan sand bodies are favorable oil and gas reservoirs, so the study on its sedimentary characteristics has important guiding significance for hydrocarbon exploration. Taking the Lower Cretaceous P Formation in BN block of BG Basin as an example, based on the theories of sedimentary petrology and sequence stratigraphy, this paper analyzed the sedimentary structure of cores, well logging curve combination forms and seismic response characteristics, and studied the regional geological features. The results show that sublacustrine fan is developed in the study area, showing positive cycle sedimentary sequence from bottom to top, and it can be divided into inner-fan,middle-fan and outer-fan sub-facies, which can be subdivided into micro-facies such as branch channel, channel edge natural levee and front sheet sand without channel. The sublacustrine fan sand bodies of P Formation are controlled by gravity flow, and they distributed along the NE-SW with fan shape. The sand bodies at the top and bottom of the branch channel of middle-fan are often sealed by dark-gray mudstones, with good oil and gas accumulation conditions. The sources of the sublacustrine fan mainly came from the northeastern fault basin, first formed large-scale fan delta depositional system in the margin of basin, then were transported to the prodelta or the farther deep lakein the form of turbidity current, and formed sublacustrine fan depositional system eventually. Favorable reservoirs of P Formation are mainly distributed in channel sand bodies of inner-fan and branch channel sandstones of middle-fan on one side of the hanging wall of fault in the northern basin.

Diagenesis characteristics of Permian reservoir in Chaiwopu Depression, Junggar Basin

Y u Ji n 1,Zhang K ui hua 2,Li n Chunm i ng 1,Zhang X i a 1,Zhang N i

2016, Vol.28(3): 95–104 Abstract ( 446 ) PDF (1651 KB) ( 493 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.013

Based on the data from core drilling, rock thin sections, X-ray diffraction, scanning electron microscope and electron probe, the diagenesis characteristics and its impact on reservoir quality of Permian Hongyanchi Formation were studied. The reservoir rock types of the Permian Hongyanchi Formation mainly include conglomerate and lithic sandstone, with low compositional maturity and textural maturity. It belongs to ultra-low porosity and ultra-low permeability reservoir, with dissolved intergranular pores as the chief accumulation space. The reservoirs of Hongyanchi Formation now are in the A stage of mesodiagenesis, and the main diagenesis include compaction, cementation, dissolution and replacement. The compaction caused the losing of primary pores, and it is the predominant reason for the destruction of reservoir quality in the study area. The cementation of clay minerals made the reservoir properties poor.The cementation of carbonate and zeolite has two different influences on reservoir quality. The carbonate and zeolite cements can not only preserve some primary intergrannular porosity by supporting clastic particles and weakening the degree of mechanical compaction, but also provide the abundant dissolved matter, making a large number of secondary pores produced. Dissolution is the most important factor for improving the reservoir quality in the study area. On the one hand, dissolution can produce a large number of secondary pores; on the other hand, dissolution is positive to petroleum migration by connecting pores and fractures.

Pre-stack amplitude-preserved ability about several seismic data processing methods

Wang Jing 1,Sun Zandong 2,Wu Jie 1,Su Qin 1,Zang Shengtao

2016, Vol.28(3): 105–112 Abstract ( 544 ) PDF (1068 KB) ( 599 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.014

The amplitude-preserved processing has a great significance on reservoir and liquid prediction. In order to study the amplitude-preserved ability of pre-stack processing method, some processing methods including geometry compensation, offset regularization and gather muting, were taken for example and studied in details in many aspects.Firstly the degree of amplitude preservation of these details in theory was analyzed. Then taking the seismic data processing of practical survey for example, the seismic profiles and gathers before and after processing were compared,and the change of AVO amplitude curves in target horizon was analyzed and the effects of these details on the elastic parameters calculation were evaluated. The result shows that to study the amplitude-preserved ability of pre-stack processing method is necessary, and geometry compensation, offset regularization and gather muting all have significance on the amplitude-preserved ability of seismic data and pre-stack AVO inversion.

Research and application of log reconstruction based on multiple regression model

Wang Junrui，Liang Liwen 2,Deng Qiang 2,Tian panpan 2,Tan Weixiong 2

2016, Vol.28(3): 113–120 Abstract ( 582 ) PDF (824 KB) ( 776 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.015

There are certain correlations among formation lithology, physical properties, hydrocarbon potential and electrical property (logging curve). Different logging curves often reflect different formation properties. It is difficult to describe the mathematical relationship among these curves through one single function. Multiple regression technique is a useful tool for dealing with the correlation among variables. At present, it has been applied widely. Multiple linear regression model is often used in various literature to describe the relationship of formation electrical property. Although it may acquire effective results for analyzing simple formation characteristic relationship, the effects of this model are often unsatisfactory due to the increasing of various geological influencing factors. Therefore, on the basis of conventional linear multiple regression model, nonlinear multiple regression models were established in this paper, and the complex nonlinear problem was simplified to a linear problem which is relatively simple to handle, which enhances the feasibility of multivariate regression technique. Meanwhile, optimal methods to select multiple regression parameters and models were established, which provides technical support for obtaining the optimum regression results. At last, the concrete meaning of log reconstruction technology in geology and engineering operation was discussed, and the feasibility is proved by citing three application cases.

Deduction and application of productivity formula for horizontal well with producing water in tightsandstone gas reservoir

Yuan Lin,Wang Chaoming,Li Xiaoping,Hu Xinjia,Zeng Li

2016, Vol.28(3): 121–126 Abstract ( 508 ) PDF (666 KB) ( 462 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.016

Tight sandstone gas is unconventional natural gas resources with great potential at present, but because of the gas reservoir with low porosity and low permeability and the effect of gas well producing water, the seepage of the fluid in the gas reservoir will no longer meet the traditional Darcy ’ s law. Based on the Joshi ’ s theory on productivity of horizontal well, considering the effect of gas well producing water, stress sensitivity, slip effect and high-speed non-Darcy flow of gas on productivity, this paper defined the generalized pseudo pressure of gas-water two phase, and used the seepage theory of gas-water two phase to deduce a new binomial productivity formula of horizontal well with gas-water two phase in tight sandstone gas reservoir. Case study and correlation shows that the absolute open flow calculated by new formula has a small relative error with that calculated by gas well-testing, just 6.60%, which indicates that the new formula will beof highaccuracy. Sensitivity analysis shows that as the increasing of volume ratio between water and gas and stress sensitivity index, the absolute open flow of horizontal well will decrease, while as the increasing of slip factor,the absolute open flow will become increasing as well.

Application of forward modeling to study of sand body connectivity in X well field of Bohai Oilfield

Zhang Jingsi， Chuai Yuanyuan， Bian Li’en

2016, Vol.28(3): 127–132 Abstract ( 521 ) PDF (843 KB) ( 689 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.017

Restricted by seismic data quality and influenced by the sedimentary characteristics of braided facies, it is difficult to identify the sand body connectivity of upper Guantao Formation of Neogene in X well field through conventional seismic attribute analysis and 90-degree phase conversion technique. This paper used forward modeling to distinguish the sand body connectivity in the study area. First of all, based on the drilling data and seismic data,this paper built different geologic models according to the sand body sedimentary characteristics of the upper Guantao Formation in X well field, and carried out forward modeling; then analyzed the seismic response characteristics of the models, discussed the influence of sand body lateral connectivity on seismic reflection characteristics,and compared with the actual seismic waveform to confirm the connectivity and the boundary of the main sand bodies in the upper Guantao Formation; finally verified the reliability of the forward modeling by the drilling data.The results show that the forward modeling can realize high precision simulations of geological model, and can effectively solve the multi-solution problem of sand body connectivity as a supplementary means. This technology has a certain value on extension and application for the research on sand body connectivity in exploration stage.

Influence of produced liquid reinjection way on oil displacement effect:A case study from J block in Liaohe Oilfield

Yao Zhenjie 1,Ma Yongjing 2,Jin Zhi,Yan Wenhua 3,Zheng Xiaosong

2016, Vol.28(3): 133–136 Abstract ( 429 ) PDF (236 KB) ( 545 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.03.018

Because of high water cut for most oil wells, strong reservoir heterogeneity and serious interlayer contradiction,surfactant/polymer compound flooding was carried out to enhance oil recovery in J block, Liaohe Oilfield. However,there are large amounts of produced liquids during surfactant/polymer compound flooding, which is not environmental,and the dealing cost is high. Through simulating produced liquid of surfactant/polymer compound flooding, displacement experiment was proceeded to optimize reinjection method and study its feasibility. The results show that produced liquids with high content of polymer can be used as pre-slug directly and subsequent protection slug. Oil recovery can be enhanced exceed 20% with different reinjection methods. The produced liquid reinjection can not only save the amount of polymer, but also solve the problem of effluent dealing.