ABSTRACTS

Vol.32 No.5, Sep.2018

01 Hydrocarbon accumulation characteristics of complex reservoirs outside the source area in Chunguang oilfield

LI Weicai et al (Exploration & Development Research Institute of Henan Oilfield Company, SINOPEC,Zhengzhou, Henan 45000)

Chunguang oilfield is a complex oil and gas accumulation area with multi-oil supplies, multi-transport systems and multi-oil products. Effective source rocks are not developed locally in the Chaipaizi uplift, and the hydrocarbon supply distance is about tens to hundreds of kilometers, which is a typical reservoir outside the source area. As a result, the reservoir forming conditions in Chunguang oil field are complex, and the identification of hydrocarbon traps is difficult, and the reservoir forming characteristics are unique. Based on the analysis of oil and gas sources, the oil and gas transmission systems are analyzed from three aspects of fault, sand plate and unconformity surface. The reservoir forming model of key oil-bearing well area is established, and the characteristics of oil and gas accumulation are summarized. The results show that Chunguang oilfield has obvious characteristics of 'bidirectional hydrocarbon supply', and oil and gas transport and accumulation mainly through the compound transport system composed of unconformity surface,plate sand and fault surface.

Key words:Chunguang oilfield； Chepaizi uplift；transportation system； reservoirs outside the source area；hydrocarbon accumulation characteristics

06 Oil and gas reservoir types in Kurdish region of Iraq and its distribution characteristics

HE Pengfei et al (Sinopec International Petroleum Exploration Production Corporation, Beijing 100029)

Kurdish region of Iraq belongs to the northern part of Zagros basin, which is a foreland basin with the most abundant conventional oil and gas resources in the world.Through detailed analysis of the hydrocarbon accumulation environment and structural characteristics of typical oil and gas reservoirs in this region, it is believed that under the compression environment affected by the foreland basin evolution, the oil and gas reservoir types in different parts of the foreland basin are different,which can be divided into two major categories, the ones controlled by faults and the ones not controlled by faults and it is further divided into seven sub-categories, among which the thrust anticline traps and the footwall anticline traps in the folded belt of Kirkuk area are the favorable exploration targets for oil and gas, while the low-amplitude anticline and the transform fault in Mosul area is favorable for oil and gas accumulation with low exploration degree, which is the key target of oil and gas exploration in the future.

Key words：Kurdish region of Iraq； basin evolution；oil and gas reservoir types

12 Sedimentary characteristics of Yingcheng formation in Longfengshan area of Changling fault depression

LUAN Ying (Exploration & Development Research Institute of Northeast Oil and Gas Company, SINOPEC,Changchun, Jilin 130062)

In the western structural belt of Longfengshan area of Changling fault depression, there developed the braided river delta sedimentary system, two sub-facies of delta plain and delta front, and six microfacies. While in the southeast slope belt, there developed the fan delta sedimentary system, fan delta front sub-facies and four microfacies. In the sedimentary period of Yingcheng formation, there were three kinds of source supplies, namely the metamorphic rock source area in the southwest, the magmatic rock source area in the south and the magmatic rock source area in the southeast. The multi-physical source leads to a strong regional zonation of rock and mineral components and the great difference in composition. During YingⅦ sand group to YingⅢ sand formation sedimentary period, the sedimentary sand bodies of different provenances carried forward from south to north, with increased material supply capacity and gradually expanded sedimentary range.

Key words:Changling fault depression；Longfengshan area； Yingcheng formation； sedimentary characteristics

18 Difference analysis of Jurassic reservoir controlling factors in western area of Sichuan basin

LIU Bai et al (Northwest Sichuan Gas Mine of Southwest Oil and Gas Company, PetroChina, Jiangyou,Chengdu 621741)

Through the observation of core and cuttings slice,combined with particle sizes, physical properties, thin slice and so on, the controlling factors of reservoir differentiation are analyzed. The Jurassic reservoir consists of distributary channel sand body and mouth bar sandstone,the physical properties of the reservoir are controlled by sedimentation and diagenesis. Deposition mainly affects the physical properties of the reservoir through sedimentary microfacies and grain sizes, the coarse sand distributary channel and estuarine dam have the best physical properties of feldspar sandstone by Longmen mountain provenance body. Diagenesis controls pore evolution, and the destructive diagenesis of Shaximiao formation is stronger than that of Penglaizhen formation. In the sand body of mouth bar from Shaximiao formation and distributary channel sand body of Penglaizhen formation, the destructive diagenesis is weaker while the dissolution of easily dissolved minerals is stronger. After the diagenesis,the reservoir of the sand body of mouth bar from Shaximiao formation and the distributary channel sand body from Penglaizhen formation reserve much reserve space, which is a favorable exploration and development target.

Key words：western area in Sichuan basin； Jurassic；reservoir characteristics； controlling factors

23 Geochemical characteristics of hydrocarbon source rocks in Naiman sag

TIAN Ya (Exploration & Development Research Institute of Liaohe Oilfield Company, PetroChina, Panjin,Liaoning 124010)

There are three sets of source rocks developed in lower cretaceous Naimen sag, namely Shahai formation,upper part of Jiufotang formation and lower part of Jiufotang formation, among which the organic abundance of source rocks from Shasha formation is higher, the kerogen type is dominated by type I and type II1, which is in immature–under mature stage and believes to be the middle grading from comprehensive evaluation. The oil generation capacity of the upper Jiufotang formation is poor, while the organic abundance of source rocks in the lower part of Jiufotang formation is high, the kerogen type is dominated by type I–II1, which is in mature stage and believes to be good source rocks and the main source rock formation in Naiman sag. The source rock is developed in a strong oxygen-free environment, and the parent of organic matter is mixed with algae and supplemented by higher plants.

Key words: Naiman sag； hydrocarbon source rocks；geochemical characteristics

40 A simplified method of PVTsim simulation of hydrocarbon-containing saline inclusions and its application

WANG Yuhui et al (China University of Petroleum(Beijing), Beijing 102249)

In the process of using PVTsim to simulate the formation of the paleo-pressure, the clear relation between the simulation results of volume ratio of gas to liquid and the trapping pressure was found, the functional relation between the ratio of gas to liquid and the trapping pressure was given, then the ratio of gas to liquid measured under the room temperature in laboratory was added into the formula and finally the simplified method of hydrocarbon-containing saline inclusion was obtained, which is convenient to simulate the pressure of mass inclusion samples and provide a reference for the correcting of the components of inclusions and the simulation results. The method was applied to simulate the evolution process of fluid pressure in Paleozoic strata of well Lin-1 in southeast Sichuan, the results showed that the overpressure of well Lin-1 generally existed during early Paleozoic, the pressure coefficient of the early Cretaceous was more than 2.0. In late Cretaceous, the formation depression declined rapidly, and it is normal in present stratum, which shows that the late strong tectonic uplift had a significant damage to the overpressure of the stratum.

Key words:hydrocarbon-containing saline inclusions； fluid pressure evolution； pressure coefficient； trapping pressure.

44 Microscopic pore structure and movable fluid saturation characteristics of Chang 8 tight sandstone reservoir of Honghe oilfield

GAO Hui (Exploration & Development Research Institute of North China Oil and Gas Company, SINOPEC,Zhengzhou, Henan 450000)

The microscopic pore structure of tight sandstone reservoir is complex, the parameters of microscopic structure characteristics obtained by the conventional method are difficult to characterize the reservoir properties and the movable fluids. Based on the conventional methods of the cast thin section, the scanning electron micro-scope, and the physical properties analysis, the unconventional methods such as constant velocity mercury injection and nuclear magnetic resonance (NMR)were adopted to determine the parameters characteristics of reservoir microstructure pore structure and the relationship between the physical properties and movable fluid saturation. The results show that the throat radius is not related to the reservoir physical property, the throat radius and pore-throat ratio are the main factors affecting the reservoir permeability and seepage ability, among which the lower the permeability, the higher the extent of the throat radius, when the permeability is higher, the pore-throat ratio influence degree is higher.

Key words:Honghe oilfield； tight sandstone reservoir； microscopic pore structure； movable fluid

52 Study and application of interlayers in heavy oil reservoirs with edge and bottom water in Bohai A oilfield

WANG Yue et al (Bohai Oilfield Research Institute,Tianjin Company of CNOOC (China) Co., Ltd., Tanggu,Tianjin 300459)

The interlayer identification technique of well points based on logging response analysis and the description technique of interlayers between wells based on seismic attribute analysis, the study on sedimentary characteristics and the interlayers of the oil-bearing strata from Minghuazhen formation in heavy oil reservoirs with edge and bot-tom water in Bohai oilfield A oilfield was carried out. The results show that there are 4 types of interlayers in this area, which can be divided into strong occlusion,medium occlusion and weak occlusion. Combined with the numerical simulation method, three types of remaining oil distribution patterns are proposed, including the top area of the secondary bottom water reservoir between oil wells, the unexploited area under the interlayer and the local pure oil area in the interlayer of transition zone.Meantime, the reliability of the interlayer recognition is further verified by combining with the actual well dynamic data, which provides a basis for further exploring the remaining oil in the study area.

Key words:Bohai A oilfield； heavy oil reservoir； interlayer； remaining oil distribution

56 Characteristics of low resistivity oil layers and its origin analysis in east area of Xixiagou in Santanghu basin

FENG Yaqin et al (Exploration & Development Research Institute of Tuha Oilfield Company, PetroChina,Hami, Xinjiang 839009)

Through thin section identification and mercury injection, in combination with logging data and formation water analysis, the study on the low resistivity oil layers from Xishanyao formation in east area of Xi'xiagou of Santanghu basin was carried out. The results indicate that the main lithology is lithic sandstone and feldspathic lithic sandstone, with lower compositional and texture maturity, the reservoir space is dominated by residual intergranular pores and dissolution inner pores, and the sedimentary environment plays a key role in the formation of low resistivity oil layers, which is mainly due to the massive distribution of siderite and pyrite and high formation water salinity.

Key words:Santanghu basin； east area in Xi'xiagou；low resistivity reservoir； reservoir characteristics

70 Research on EOR by SP flooding in heavy oil reservoir of Gucheng oilfield

SHE Wenchang et al (Zhongyuan Engineering Design co., LTD, SINOPEC, Zhengzhou, Henan 450000)

The viscosity of underground crude oil in Gucheng oilfield averages 650 mPa·s. In order to improve the development effect of water flooding in heavy oil reservoirs, the polymer/surfactant binary compound flooding tech nology was studied, and the formulation of binary compound system was optimized. Compared with water flooding, the viscosity of the binary composite system increased from 0.57 mPa·s to 81.1mPa·s, the interfacial tension decreased from 19.2 mN /m to 2.70×10–2mN /m,and the number of capillary tubes increased by 5 orders of magnitude. The emulsifying property of binary composite system can reduce the viscosity of crude oil, improve the viscosity of displacing fluid and further improve the fluidity ratio. The study shows that the binary compound flooding technology can improve the recovery rate by 15.99% and can be applied in the field of common heavy oil reservoirs with crude oil viscosity of 650 mPa·s.

Key words:Gucheng oilfield； heavy oil reservoir；surfactant-polymer flooding； enhanced oil recovery

73 Water breakthrough time prediction of oil wells in the bottom water reservoir

YUAN Qingyun (Exploration & Development Research Institute of Northwest Oilfield Company, SINOPEC, Urumuqi, Xinjiang 830011)

Based on the theory of seepage mechanics, a model for calculating water breakthrough time of the bottom water reservoir is established, and the formulas of water breakthrough time of oil wells in the bottom water reservoir without interlayer and with interlayer are deduced.Combined with the actual geological characteristics of bottom water reservoir, the values of three parameters in the formula are demonstrated, including porosity, oil saturation of two-phase flow interval and permeability coefficient of reservoir. The water breakthrough time of three wells with interlayers is calculated by the derived water breakthrough time formula. Compared with the actual water breakthrough time, the relative error is no more than 9% and calculation accuracy meets the actual requirement of oilfield development.

Key words:bottom water reservoir； water breakthrough time； prediction model

76 Enhanced liquid technique for narrow channel reservoirs under small difference between formation and bubble point pressure

PAN Jie et al (Bohai Oilfield Research Institute,Tianjin Company of CNOOC (China) Co., Ltd., Binhai New Area, Tianjin 300459)

The narrow channel oil reservoirs in Bohai area under small difference between formation and bubble point pressure have entered the stage of medium and high water cut, with rapid production decline and great difficulty in stable yield, while the big-pump enhanced liquid technique is an effective stimulation method. However, it is difficult to determine the reasonable enhanced liquid amplitude because the flow characteristics of narrow channel reservoir is different from the complete-structure reservoirs and it is easy to degas for small difference between the formation and bubble point pressure. Based on the flow percolation equation of narrow channel considering the influence of river boundary, the specific liquid recovery indexes of different water-cut stages were determined.According to IPR curve of gas phase, the reasonable production pressure difference under different formation pressure is determined. Combined with the specific liquid recovery index and reasonable production pressure difference, the reasonable liquid extraction range of this type oil reservoir at different water cut stages under different formation pressure was determined. This method is applied to field test which has resulted in good effects of increasing production and can provide theoretical guidance and production experiences for offshore narrow channel reservoirs.

Key words:narrow channel reservoir； BZ oilfield；small difference between reservoir and bubble point pressure； enhanced liquid amplitude

87 Remaining oil distribution of polymer flooding by heterogeneous microscopic model

WANG Xinran et al (Tianjin Company, CNOOC(China) Co., Ltd., Tianjin 300459)

Remaining oil recovery of offshore polymer flooding oilfield is closely related to the distribution law and main controlling factors of remaining oil. However, the remaining oil core displacement experiment cannot get a clear understanding of the remaining oil distribution. By using the heterogeneous microscopic pore model, the distribution pattern of remaining oil in Bohai J oilfield under the different displacement media and different displacement velocities, as well as the influence of different displace ment media on the main remaining oil distribution pattern were studied. The experimental results showed that remaining oil distribution effected by driving velocity significantly under the same driving medium, polymer and surfactant driving system is the most effective under the same driving velocity.

Key words:Bohai J oilfield； heterogeneous microscopic model； remaining oil distribution

95 Application of network fracturing technique for horizontal wells of ultra-low permeability oil reservoir in S block, Ordos basin

LIANG Weiwei et al (Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi 710075)

Chang 8 oil reservoir in S block of Ordos basin belongs to an ultra-low porosity and ultra-low permeability tight sandstone reservoir. Its development is not ideal, and the purposes of economic and effective exploitation have not been achieved in conventional single well with low well production, fast decline on the production and poor efficiency of water flooding. Therefore, a network fracturing technology in horizontal well was tested. According to the relevant data of S block, the difference coefficient of the horizontal principal stress of the target layer meets the ground stress condition of fracture network fracturing,which can produce fracture network. According to the requirements of fracture network fracturing, four horizontal well fracture network fracturing tests were completed in the research area. In the early stage after pressure, the average single well daily produced 40.9 m3of liquid and 23.3 t of oil., which obtained better development benefits.

Key words:Ordos basin； ultra-low permeability sandstone reservoir； horizontal well； network fracturing；microseism fracture monitoring

99 A method of permeability treatment by clustering analysis and numerical simulation

YAO Junbo et al (Tianjin Company, CNOOC (China)Co., Ltd., Tianjin 300459)

In the process of reservoir numerical simulation, the permeability, oil saturation, porosity and other important physical parameters are derived from the geological mode.The accuracy of these parameters is particularly important for making various development programs, among which the permeability has the anisotropic characteristic,while the permeability can be only derived from the model in one dimensional. The accuracy is greatly reduced by determining permeability values in three dimensions according to the empirical assignment. The Ward method clustering analysis method will be first introduced into reservoir numerical simulation, and then the permeability data can be obtained by spatial geometry processing,which greatly improves the accuracy of numerical simulation. This method has been applied well in production examples, which provides a strong basis for the formulation of efficient development program of oilfield.

Key words:reservoir numerical simulation； permeability； anisotropy； clustering analysis

103 Study on core dielectric characteristics and saturation model

LI Junjian et al (School of Geophysics and Information Engineering, China University of Petroleum (Beijing), Beijing 102249)

The relative dielectric constant of artificial sandstone core was measured, and the relationship between relative permittivity and saturation, porosity and mineralization were studied in the frequency band of 20 ～1 000 MHz. The results show that the core's relative permittivity has a good linear relationship with saturation and porosity,and the mineralization has a great influence on the relative dielectric constant at low frequency. Based on the analysis of experimental data, combined with the existing dielectric saturation model and based on Maxwell-Garnett theory, a multi-frequency dielectric mixed interpretation model suitable for sandstone is presented.

Key words:relative dielectric constant； core model；core dielectric characteristics； influencing factor

107 Exploration and application of multi-stage temporary plugging turning to repeated fracturing technology inHenan oilfield

SUN Binfeng et al (Petroleum Engineering Research Institute of Henan Oilfield Company, SINOPEC, Nanyang, Henan 473132)

Repeated fracturing is an important means to maintain the productivity of old wells, however, with the increase of repeated fracturing, the effect of oil increase and the effective period of oil production will de-crease greatly. The temporary plugging turning to repeated fracturing can realize new fractures in the old fractures and communicate with larger oil drainage area, thus improving oil well production. According to the physical model experiment of fracture steering mechanism, the mechanism of fracture building and extension is understood. The experimental results show that the repeated fracturing fractures are mainly extended along the old fractures, and the limit of the stress difference of the forced turning of the old fractures is 8 MPa. Field test results show that the selected high strength and low damage fracture steering agent has successfully achieved multistage fracture steering, and the application effect is good.

Key words:Henan oilfield； multi-stage temporary plugging steering； repeated fracturing； fracture diverter

110 Practice and understanding of fracturing transformation of shale reservoirs in Zhongmou shale gas block

SUN Yonghao et al (Henan Land and Resources Development Investment Management Center, Zhengzhou,Henan 450006)

Based on the analysis of geology, rock mechanics and stress characteristics, the compressibility of Mouye-1 well was evaluated comprehensively. The results show that the favorable factors are high brittleness index, natural fracture development and large difference in ground stress. According to reservoir geology and engineering characteristics, the fracturing scheme was determined.The fracturing parameters are optimized and adjusted by numerical simulation. According to the fracturing pressure history fitting analysis and micro-seismic monitoring results, complex fractures of a certain scale are formed after pressure and the reconstruction range is relatively large. The daily output of 1,256 m3was obtained after gas test, and significant discovery of shale gas exploration in Henan province was obtained, which proves this block has a good prospect of exploration.

Key words:Henan Zhongmu； shale reservoir； fracturing technology； natural fracture

113 Rock mechanical parameters of Dabei-Keshen region calculated by using the array acoustic logging data

KANG Liwei (Logging Center of China petroleum logging co., LTD., PetroChina, Xi 'an, Shaanxi, 710054)

Taking the data of X and Y wells in Dabei-Keshen region as an example, the related formation rock mechanical parameters were calculated by using the array acoustic logging. The results show that the mudstone formation has high rock strength, followed by gypsum formation, and the sandstone has low formation strength. The higher the shale content, the greater the tensile, shear and compressive strength, and the lower the Biot coefficient. The method of array acoustic logging can accurately extract the time difference between the horizontal and vertical waves of strata, which has significant advantages in calculating the mechanical parameters of strata. The method can save expensive testing cost of elastic mechanical parameters and can predict and judge the development of deep strata.

Key words:Dabei-Keshen region； array acoustic logging； slow extraction； rock mechanical parameters