Table of Content

25 August 2020, Volume 27 Issue 4

Previous Issue    Next Issue

Geologic Exploration

Shale Gas Reservoir and Gas-Bearing Properties of Middle Yangtze Niutitang Formation in Western Hubei

Xu Lulu, Liu Zaoxue, Wen Yaru, Zhou Xianghui, Luo Fan

2020, 27(4):  1-9.  DOI: 10.3969/j.issn.1006-6535.2020.04.001

Asbtract ( )   PDF (4288KB) ( )  

References | Related Articles | Metrics

The Lower Cambrian Niutitang Formation is one of the major shale gas exploration fields in western Hubei. In order to further understanding the shale gas reservoir and gas-bearing properties of the Niutitang Formation, drilling and stratigraphic profile data were used to comprehensively analyze the rock formation, sedimentary facies, shale burial depth, shale thickness, geochemical properties, reservoir physical and gas-bearing properties. Research indicates that the Niutitang Formation in western Hubei can be divided into two members according to the lithofacies. Shallow-water and deep-water shelf facies are dominant in this area with the wider distribution of deep-water shelf facies. There are three underwater uplifts in Xingshan County-Yichang City. Laifeng County-Enshi City and Shennongjia shows the maximum shale thickness of more than 200.0 m. The TOC of Niutitang Formation gradually decreases from bottom to top. The Xianfeng-Hefeng area shows a high regional TOC distribution and the corresponding TOC is dominated by high and extra-high levels of greater than 2.00%. The R_o is about 2.0%～3.5% in high maturity stage. The mineral components are dominated by clay minerals and quartz, and the clay mineral content gradually increases from bottom to top. The Niutitang Formation is considered as a low-porosity and ultra-low permeability reservoir. The gas content of Niutitang Formation increases rapidly and then gradually decreases. The lower part of the Niutitang Formation shows a maximum gas content in the longitudinal direction and the relatively high gas content laterally distributes in the southeast flank of the Huangling anticline. Comprehensive analysis suggests that the favorable exploration zones are locates in the wide and gentle anticline wings within the deep-water shelf facies and far away from the regional fault zone. This research could provide certain reference for the shale gas exploration well deployment in the Niutitang Formation of Western Hubei.

Sandy Braided River Sandbody Configuration and Remaining Oil Distribution Pattern

Suya Latu, Li Qian, Zhang Bo, Du Fashu, Zhang Qi, Xu Shiqi

2020, 27(4):  10-18.  DOI: 10.3969/j.issn.1006-6535.2020.04.002

Asbtract ( )   PDF (4317KB) ( )  

References | Related Articles | Metrics

In order to identify the effects of different-order sandbody configuration patterns, internal interlayer and rhythm within braided-river on the remaining oil distribution in the middle-late development stage, The braided river and lithofacies of the middle Jurassic Yungang Formation in the Tieluqiao profile of Shanxi Datong were detailed characterized and analyzed based on the field outcrop lithology and sedimentary structure. Result indicates that there are nine lithofacies categories can be identified and three genetic sandbody categories, including channel sandbody, channel bar sandbody and point-bar sandbody. The point-bar sandbody is classified into the major genesis sandbody in the braided river channel from fine dissection of longitudinal sandbodies and detailed modern river sedimentation. In addition, 9 remaining oil enrichment patterns were established by combining with the fourth-order and fifth-order configuration interfaces and the deployment of injection-production well pattern. This research could provide a reliable reference for further remaining oil recovery and enhancing oil recovery for the sandy braided-river reservoirs in the Yungang Formation.

Basement Fault Characterization and Hydrocarbon Accumulation in Fuling of Southeastern Sichuan

Pan Lei, Xu Zuxin, Li Rangbin, Zou Yutao

2020, 27(4):  19-25.  DOI: 10.3969/j.issn.1006-6535.2020.04.003

Asbtract ( )   PDF (2932KB) ( )  

References | Related Articles | Metrics

In order to clarify the hydrothermal dolomite gas reservoir enrichment pattern of Maokou Formation, the basement fault properties, formation and evolution and their significance for the hydrocarbon accumulation in the Maokou Formation and establish a hydrocarbon accumulation mode. Research indicates that there are three tectonic styles in the basement fault cross section, including "Y" and reverse "Y" style, "flower style" and upright style. Three basement faults were identified laterally, including No.15, No.15-1 and No.16 basement faults, which all show a northwest to southeast distribution. The basement fault indicates stratified properties in the longitudinal direction and segmentation along the fault strike. The middle and upper tectonic layer activity of the basement fault No.15 and No.15-1 is higher than that of the basement fault No.16, and the west section activity is higher than that of the east section in the basement fault No.15. The basement fault controls the formation and distribution of Maokou Formation hydrocarbon reservoirs. The dolomite reservoirs show a zonal distribution along the two sides of basement fault. The underlying Silurian sourcerock contribution increases with the decrease of distance to the basement fault. The well test production increases with the increase of gas content. An "on-source accumulation, dual-source hydrocarbon supply" hydrocarbon accumulation mode was established by comprehensively considering the basement fault, sourcerock and reservoir development pattern. This research could provide certain guidance for further understanding the Maokou Formation hydrothermal dolomite in Fuling, and it can also offer certain reference for the hydrocarbon accumulation characterization in other basement fault development areas.

Main-Controlling Factor Analysis of Hydrocarbon Accumulation in the Bedrock Buried Hill of Lishu Fault Depression and Its Exploration Prospect

Cheng Jian, Zhou Zhuoming, Duan Tiejun, Yang Hao, Song Zhenxiang

2020, 27(4):  26-32.  DOI: 10.3969/j.issn.1006-6535.2020.04.004

Asbtract ( )   PDF (1963KB) ( )  

References | Related Articles | Metrics

The Lishu fault depression in the southern Songliao Basin is characterized by complex bedrock structure and diverse buried hill development mechanisms. The major challenges for further evaluation of buried hill hydrocarbon exploration potential include buried hill distribution prediction, reservoir performance evaluation and hydrocarbon accumulation patterns. Geological and geophysical techniques were adopted to analyze the main controlling factors of buried-hill hydrocarbon accumulation based on the drilling core test. Result indicates that the buried hill development is dependent on basin-controlling fault, fold structure and reverse structure. Bedrock reservoir is generally featured by low porosity and low permeability, and structural fractures are the key aspect to improving reservoir performance. Generally, there is a increasing trend for the fracture development closer to the fault zone. Hydrocarbon enrichment and accumulation in the buried hill depends on the contact patterns of bedrock and source rock, consistency between fracture direction, opening level and hydrocarbon migration mode. There is a direct contact between bedrock buried hill and source rock in Sangbei and Sangnan, and favorable hydrocarbon supply condition is conductive to bedrock hydrocarbon accumulation. The bedrock buried hill shows a relatively low amplitude in the central tectonic belt, Qikeshu, Qinjiatun and other regions which are far away from the major fault. The basement contacts with source rock as fault and unconformity, which is favorable to bedrock hydrocarbon accumulation. A total of more than 20 buried hill traps were identified in the Lishu fault depression, indicating great hydrocarbon exploration prospect. The western Sangshutai buried hill zone and the central structural buried hill zone are considered as the major zones for further hydrocarbon accumulation. This research could provide certain theoretical reference for the bedrock hydrocarbon resource prediction and exploration.

Source-Rock Characterization and Main-Controlling Factors in the Northern Guaizihu Depression of Yin'e Basin

Jiang Hang, Zeng Deming, Liu Huchuang, Hei Wei, Pan Binfeng, Xie Xiaobin

2020, 27(4):  33-40.  DOI: 10.3969/j.issn.1006-6535.2020.04.005

Asbtract ( )   PDF (1334KB) ( )  

References | Related Articles | Metrics

In order to enhance the hydrocarbon exploration level in the Guaizihu Depression and determine the effective source-rock distribution and controlling factors, the source-rock in the Well Wen1 was characterized and the corresponding main-controlling factors were analyzed by adopting organic geochemistry, sedimentary sequence and tectonic evolution analyses. Research indicates that the source-rock in the whole region shows a relatively low organic matter abundance due to the comprehensive influence of sedimentary sequence and structure. Highstand systems tract is favorable to the organic matter enrichment. The corresponding organic matter consists of sapropelic-humic and humic categories. The thermal evolution of organic matter shows a quite great difference. Muddy rock development can promote the early thermal evolution process, and the late structure uplift greatly shortens the local hydrocarbon generation time, so the organic matter maturity in this region is from immature to high mature. The source-rock distribution is greatly dependent on the faults and sedimentary evolution. This research could provide certain reference for the geological understanding of northern Guaizihu Depression.

Pore Structure Characterization and Micro-Heterogeneity of Carboniferous-Permian Organic-Rich Shalein Julu

Yao Shuanghong, Li Xueyuan, Li Peng, Wang Huijun, Chen Shangbin

2020, 27(4):  41-48.  DOI: 10.3969/j.issn.1006-6535.2020.04.006

Asbtract ( )   PDF (2102KB) ( )  

References | Related Articles | Metrics

In order to reveal the fractal performance and micro heterogeneity of riched organic in shale pores, X-ray diffraction, scanning electron microscopy and low temperature liquid nitrogen adsorption were used to qualitatively and quantitatively characterize the pore structure of riched organic in shale in Julu. The FHH model was used to calculate the fractal dimension of pores and discuss the influencing factors of micro heterogeneity. Research indicates that the shale mainly composed by clay minerals and quartz. The corresponding clay minerals are dominated by illite-smectite mixed layer, illite and chlorite. The pores mainly consist of organic pore, intergranular pore and micro fracture. The micro heterogeneity shows a difference for different pore size intervals, and there is a stronger micro heterogeneity in the range of 4.34～100.00 nm. The fractal dimension is positively and negatively related to clay minerals and brittle minerals respectively. The pore micro heterogeneity is also dependent on the structure and diagenesis. This research could provide certain theoretical reference for the shale gas exploration in Julu.

Research and Application of Scattered Wave Imaging Technology in Buried-Hill Seismic Data Processing

Liu Shiguang

2020, 27(4):  49-53.  DOI: 10.3969/j.issn.1006-6535.2020.04.007

Asbtract ( )   PDF (3779KB) ( )  

References | Related Articles | Metrics

Buried hill reservoir s are considered as one of the major hydrocarbon exploration areas in the Liaohe Depression, and the corresponding reservoir space is dominated by microfracture and micropore. The seismic data inside the buried hill is characterized by complicated wave fields and unclear reflections. Traditional reflected wave imaging is limited in the internal structure identification and buried-hill hydrocarbon exploration. A new scattered wave imaging technology was proposed to realize high-resolution seismic data imaging by suppressing seismic reflection wave energy and strengthening scattered wave energy. The weak seismic scattered signal inside the buried-hill can be imaged to characterize the fracture properties within the buried hill under complex geological setting. This technology was successfully applied to characterize the complex structures of Shuguang buried hill zone in Liaohe Oilfield, which could also provide certain reference for the similar seismic data processing.

Hydrocarbon Accumulation Main-Controlling Factor Analysis of Chang₂ Reservoir in Zhijing-Ansai of Ordos Basin

Feng Shunyan, Zhang Xiaohui, Li Cheng, Jing Xianghui, Sun Lei

2020, 27(4):  54-59.  DOI: 10.3969/j.issn.1006-6535.2020.04.008

Asbtract ( )   PDF (1465KB) ( )  

References | Related Articles | Metrics

In order to understanding the complex geology of Chang₂ oil reservoir in Zhijing-Ansai and determine the main-controlling factors of hydrocarbon enrichment, the sedimentary facies, sandbody distribution patterns, favorable traps and other hydrocarbon enrichment mechanisms were comprehensively analyzed by the researches on source-rock, sedimentary facies, favorable sandbodies, migration channels, trap conditions, etc. Result indicates that the hydrocarbon enrichment in Chang₂ oil reservoir are dependent on multiple factors, including hydrocarbon source, unconformity, low-amplitude structure, sedimentary facies, reservoir properties, caprock properties, etc. The matching between the high-permeability sandbodies at the junction of distributary channels and the near-east row nose-shaped uplift is favorable to hydrocarbon accumulation. The caprock and longitudinal sandbody structures result in the hydrocarbon enrichment in Chang₂Ⅰ³ sub-layer. There are lithology, structure-lithology and weak structure-lithology reservoir categories in Chang₂ oil reservoir due to multiple controlling factors. This research could provide certain guidance for the further exploration in Chang₂ oil reservoir.

Fracture Properties and Development Mechanisms of Sinian Dengying-4 Member in Central Sichuan

He Shun, Qin Qirong, Wang Jiashu, Li Fei, Duan Wei

2020, 27(4):  60-66.  DOI: 10.3969/j.issn.1006-6535.2020.04.009

Asbtract ( )   PDF (1362KB) ( )  

References | Related Articles | Metrics

Drilling core observation, imaging logging, seismic data and other data were used to comprehensively analyze the fracture properties and development mechanism of the Dengying-4 Member carbonate rock in Moxi of Central Sichuan by combining with uniform temperature test of inclusion. Result indicates that there is tensile fracture, small scale shearing fracture and small scale pressure-solution fracture in the Dengying-4 Member of Moxi, which is dominated by tensile fracture. There are four dominant fracture strikes, including NW, NE, WE and NS. The fractures show a high filling level and the corresponding filling materials are dolomite, muddy, asphaltene, calcite and a small amount of quartz. The fractures in the Dengying-4 Member result from three-stage tectonic movements. The first-stage fractures developed in the Act-II of Dengtongwan movement (522.0～508.0 Ma), which are dominated by NW, NS and WE fractures due to the northward subduction of the Indian plate and the eastward collision of the Eurasian plate, and the corresponding uniform temperature of inclusions is 116.6～146.3 ℃. The second-stage fractures developed in the Caledonian movement (425.0～420.0 Ma), which are dominated by NE fractures due to the collision between the Yangtze plate and the Cathaysia plate, and the corresponding uniform temperature of inclusions is 138.0～176.0 ℃. The third-stage fractures developed in the Yanshan-Himalaya movement (75.2~75.0 Ma), which are dominated by shearing micro-fractures due to the effect of Longmenshan thrust folds, and the corresponding uniform temperature of inclusions is 177.0~208.0 ℃. This research could provide certain theoretical reference and basis for the further understanding of carbonate reservoirs in the Dengying Formation.

Reservoir Engineering

Solvent-Assisted SAGD Startup Technology Adaptability in Super-Heavy Oil Reservoir

Yang Zhaochen, Yu Bing, Wu Yongbin, Wang Li, Zhang Jiahao, Tong Juan, Jiang Dan, Zhang Chonggang

2020, 27(4):  67-72.  DOI: 10.3969/j.issn.1006-6535.2020.04.010

Asbtract ( )   PDF (1477KB) ( )  

References | Related Articles | Metrics

In order to improve the low viscosity reduction rate of steam preheating, long preheating cycle, large steam consumption, uneven interwell producing degree and other problems in the dual horizontal-well SAGD with conventional steam cycle preheating, laboratory test and numerical simulation were combined to understanding the technical principle and adaptability of solvent-assisted SAGD preheating startup technology. Research indicates that the solvent-assisted SAGD is featured by small preheating cycle, low steam consumption and uniform interwell connectivity, which is applicable for the super-heavy oil reservoirs with permeability between lateral sections not less than 500 mD, oil saturation not less than 60% and the crude oil viscosity from 2.0×10⁴ mPa·s to 10.0×10⁴ mPa·s at 50 ℃. The reservoir screening principles could provide certain reference for other heavy oil reservoirs to implement solvent-assisted SAGD startup technology.

Tight Sandstone Fractal Permeability Model and Key Fractal Parameter Calculation

Zhao Jiuyu, Wang Fuyong, Yang Kun

2020, 27(4):  73-78.  DOI: 10.3969/j.issn.1006-6535.2020.04.011

Asbtract ( )   PDF (1691KB) ( )  

References | Related Articles | Metrics

In order to improve the tight sandstone permeability prediction challenges result from the poor correlation between fractal permeability model parameters and permeability and the poor 3D structure characterization with tortuosity fractal dimension, a tight sandstone permeability prediction model was established based on the fractal patterns of tight sandstone pore structure and tortuous capillary bundle model. The calculation methods of fractal dimension, tortuosity fractal dimension and characteristic length were proposed to discuss the influence of different tortuosity calculation methods on the tight sandstone permeability prediction. Research indicates that this model can effectively predict tight sandstone permeability, and the prediction is closer to that of tested value. The calculated fractal dimension shows a favorable correlation with core permeability. There is a significant difference in the tight sandstone tortuosity for different calculation methods, and appropriate tortuosity calculation method could improve the prediction accuracy of tight sandstone permeability. This research could accurately and quickly predict permeability, which will provide certain guidance for the evaluation and efficient development of tight sandstone reservoir.

Microscopic Adsorption Mechanism Difference in the Mineral Pore of Shale Gas Reservoir

Xu Chenxi, Xue Haitao, Li Bohong, Lu Shuangfang, Zhang Jian, Chen Guohui, Wang Shuai

2020, 27(4):  79-84.  DOI: 10.3969/j.issn.1006-6535.2020.04.012

Asbtract ( )   PDF (1699KB) ( )  

References | Related Articles | Metrics

The giant regular Monte Carlo molecular simulation method (GCMC) was used to study the microscopic adsorption mechanism difference for the shale gas in different mineral pores. Material Studio software was adopted to simulate the occurrences of shale gas in three mineral pore categories (kerogen, clay mineral, quartz) and explore the adsorption mechanism of shale gas in different mineral pore categories. Research indicates that the mineral adsorption capacity from high to low is kerogen, clay mineral and quartz. The great differences in adsorption capacity for organic matter, clay mineral and clastic mineral mainly result from the change of adsorption site (distribution density and adsorption intensity of adsorbate gas) on various mineral surfaces. An integral understanding of the adsorption mechanism differences for the shale gas in various mineral pore categories is favorable to the adsorbed gas content evaluation. This research could provide certain theoretical reference for the prediction of shale gas adsorption capacity in different regions.

Improvement of Injection-Production Connectivity Calculation and Its Application in Injection Allocation

Jia Lu, Shi Guowei, Shi Feng, Lan Haigang, Ji Lanmin

2020, 27(4):  85-91.  DOI: 10.3969/j.issn.1006-6535.2020.04.013

Asbtract ( )   PDF (1165KB) ( )  

References | Related Articles | Metrics

In order to quantitatively characterize the injection-production connectivity, response ratio and other key information in the waterflooding oilfield, a multiple linear regression analysis model considering variable bottom-hole flowing pressure was proposed by integrating and improving the available calculation methods for injection-production connectivity. The oil production performance can be favorably characterized by this new model to obtain a quantitative and reliable analysis for the injection-production connectivity. The injection-production response and ratio were determined and the manual analysis was significantly reduced by combining with wellgroup injection allocation model. This model had been verified by a field application in Xinjiang Oilfield, and the corresponding accuracy had been significantly improved. This research could effectively improve the efficiency and scientificity of oilfield injection-production deployment program design and promote intelligent oilfield deployment and adjustment, which could provide certain reference for the development of similar reservoirs.

Application of Advanced Water Injection Inflow Production Relation Model in Low-Permeability Reservoir

Zhang Jiqiang

2020, 27(4):  92-97.  DOI: 10.3969/j.issn.1006-6535.2020.04.014

Asbtract ( )   PDF (1403KB) ( )  

References | Related Articles | Metrics

There is a three-phase flow between water, injection water and dissolved gas in the low permeability reservoir with advanced water injection in the production process. In order to further characterize the three-phase seepage performance, the fluid flow in the reservoir was divided into oil-water two-phase seepage zones and oil-gas-water three-phase seepage zones. Based on a three-phase quasi-pressure function, a three-phase flow productivity equation with inflection point was established by considering the non-Darcy effect (starting pressure gradient, stress sensitivity). Research indicates that the test data is consistent with the calculation of three-phase seepage model after automatic fitting of non-Darcy flow parameters. Application of 4 wells shows that the production can be enhanced by about 195.0% when the production well is controlled below the inflection pressure. Multiple factors show a significant influence on the well production in the high flowing pressure stage, and the water cut is considered as the most sensitive factor. This research could provide certain guidance for the determination of reasonable bottom hole flowing pressure limit in low permeability reservoir with advanced water injection.

Application of Statistical Analysis in the Ultra-Low Permeability Reservoir Classification of Changqing Oilfield

Liu Yaru, Liu Baolei, Lei Zhengdong, Chen Xinbin, Yu Qin, Zhong Ming

2020, 27(4):  98-104.  DOI: 10.3969/j.issn.1006-6535.2020.04.015

Asbtract ( )   PDF (1251KB) ( )  

References | Related Articles | Metrics

In order to specifically improve the production and development performances of ultra-low permeability reservoirs by classification and enhance their oil recovery, a correlation analysis on reservoir parameters was conducted by comprehensively considering the geology properties and development performances. A total of 7 parameters was taken as the indicators for reservoir classification and factor analysis was used to analyze 90 ultra-low permeability blocks in Changqing Oilfield. 4 major indicators were further taken to classify these reservoirs by K-means clustering analysis method. The discriminant formulas for various reservoir categories were obtained according to discriminant analysis, which finally classified the 90 reservoir blocks into three categories and provided a comprehensive evaluation. This classification can effectively characterize the development performances of various ultra-low permeability reservoir blocks and the corresponding classification is consistent with that of actual development performance. This research could provide certain reservoir classification reference for the reasonable development of ultra-low permeability reservoirs and favorably guide the production and development of ultra-low permeability reservoir.

Interlayer Development Patterns and SAGD Enhanced Oil Recovery Technology in the Super Heavy Oil Category-III Reservoir

Wang Qian, Gao Xianglu, Luo Chihui, Meng Xiangbing, Gan Shanshan, Liu Jia

2020, 27(4):  105-112.  DOI: 10.3969/j.issn.1006-6535.2020.04.016

Asbtract ( )   PDF (2221KB) ( )  

References | Related Articles | Metrics

The Fengcheng super heavy oil reservoir is considered as a continental braided river facies deposit with well developed interlayers, especially the super heavy oil Grade-Ⅲ reservoir shows a strong heterogeneity, which results in low producing degree of lateral section, uneven steam chamber expansion and other serious problems during SAGD development and significantly influences the SAGD development performance. The interlayer development was summarized into 4 typical patterns based on the braided river reservoir development in the Fengcheng super heavy oil reservoir. The development morphology of SAGD steam chamber for the 4 typical patterns was analyzed and the corresponding technical countermeasures were proposed, including straight well assisted SAGD, multi-branch SAGD, reservoir stimulation and other technologies. A set of efficient SAGD development technology system for super heavy oil Grade-Ⅲ reservoir had been established and effectively applied in field development. This technology provides certain technical reference for the efficient development of low quality super heavy oil reservoir with SAGD and it worthy of promotion and application.

Heat Transfer Enhancing Mechanism of Deep Steam with Non-Condensate Gas

Li Zhaomin, Xu Yajie, Lu Teng, Yang Jianping, Wang Hongyuan, Shang Zhenxiao

2020, 27(4):  113-117.  DOI: 10.3969/j.issn.1006-6535.2020.04.017

Asbtract ( )   PDF (1486KB) ( )  

References | Related Articles | Metrics

In order to study the heat transfer enhancing mechanism of deep steam with non condensate gas in steam flooding, a 1D physical sand pack model was used to conduct a non condensate gas assisted steam flooding simulation experiment. The effect of non condensate gas on the steam condensation heat transfer was analyzed by a laboratory condensation heat transfer experiment. Experiment indicates that the pure steam injection shows a high steam medium heat exchange rate and a relatively small heat spread range. With the adding of non condensate gas, the steam heat spread range increases and the deep reservoir is heated, which effectively improve the steam heat utilization rate. Comparing with pure steam condensation, the growth and shedding speeds of condensed liquid drop slow down after adding non condensate gas, which leads to the generation of relatively large liquid drop. The liquid drop holds up the steam heat transfer and the non condensate gas suppresses the steam condensation. A thorough understanding of the non condensate gas hold up mechanism on steam heat transfer could provide certain guidance for the steam heat transfer enhancing and steam heat utilization improvement.

Formation Water Mobility and Influencing Factors in Tight Sandstone Gas Reservoir

Su Yuliang, Li Dongsheng, Li Lei, Gao Xiaogang, Zhuang Xinyu, Fu Jingang

2020, 27(4):  118-122.  DOI: 10.3969/j.issn.1006-6535.2020.04.018

Asbtract ( )   PDF (1473KB) ( )  

References | Related Articles | Metrics

Nuclear magnetic resonance was used to test core pore size distribution and whole-rock X-ray diffraction analysis was conducted to understanding the relationship between physical properties and formation water mobility and determine the formation water mobilities under different physical properties in tight sandstone gas reservoir.A new method for formation water mobility classification by combining with centrifugalizing and nuclear magnetic resonance was proposed to analyze the relationship between porosity,permeability,pore structure,rock mineral composition and formation water mobility. Result indicates that there is no absolute limit for the movable or immovable water, and the formation water mobility is greatly dependent on the reservoir pore structure.Mineral composition shows little effect on the formation water mobility.It is believed that the formation water can be classified into bound water, movable bound water and movable water,while there is no absolute limit for the classification of bound water saturation,movable bound water saturation and movable water saturation.The corresponding approximate values can be gained through laboratory experiment test.This research could provide certain guidance for the tight sandstone gas reservoir development and reduction of formation water production risk.

Properties and Oil Displacement Performance of Ternary Sulfonated Modified Polyacrylamide

Wu Peng, Zhang Yue, Niu Yuping, Jiang Ying

2020, 27(4):  123-130.  DOI: 10.3969/j.issn.1006-6535.2020.04.019

Asbtract ( )   PDF (1733KB) ( )  

References | Related Articles | Metrics

In order to improve the viscosity reduction of partial hydrolyzing polyacrylamides under high temperature and high salt condition, the ternary sulfonated modified polyacrylamide was synthesized by azo-redox compound initiation system. It also provided the structure characterization, property evaluation and oil displacement performance. Research indicates that the ternary sulfonated polyacrylamide molecules shows a long chain structure and the chains contact and intertwine with each other to form an irregular spatial 3D network structure. Comparing with the partial hydrolyzing polyacrylamides, the ternary sulfonated modified polyacrylamide is characterized by high viscosity, better temperature and salt resistance stability and viscoelasticity. The ternary sulfonated modified polyacrylamide indicates the maximum resistance factor and residual resistance factor, followed by comb polymer, and the partial hydrolyzing polyacrylamide indicates the minimum resistance factor and residual resistance factor. The oil displacement performance from high to low are ternary sulfonated modified polyacrylamide, comb polymer and partial hydrolyzing polyacrylamide. The recovery factor increasing rate of ternary sulfonated modified polyacrylamide decreases with the increase of concentration and temperature and the decrease of salinity. The research was applied to 13 oil production wells in the Block F30 of Shengli Oilfield. The daily oil production was enhanced to 5.2 t/d, the water cut was reduced to 90.4%, and the average cumulative oil increment per well was 685.3 t. This research is of great significance for improving economic benefits and guiding field practice in polymer flooding treatment.

Injection Parameter Optimization of Deoxidized Air Foam Flooding for Heavy Oil Reservoir and Its Field Application

Li Jingjing, Deng Changlian, Tang Xiaodong, Wang Fang, Wei Yong

2020, 27(4):  131-135.  DOI: 10.3969/j.issn.1006-6535.2020.04.020

Asbtract ( )   PDF (1862KB) ( )  

References | Related Articles | Metrics

In order to improve the gas lock,unreasonable injection parameters and other problems in the foam flooding of Lukeqin heavy oil reservoir,the deoxidized air foam flooding injection parameters were optimized by laboratory physical simulation experiment.Research indicates that a maximum recovery degree increment and a significant water cut increase can be realized by immediately carrying out deoxidized air foam flooding after water breakthrough.Alternate gas-liquid injection pattern is recommended rather than gas-liquid coinjection pattern to avoid gas-liquid separation and corrosion in wellbore.A comparable displacement performance to gas-liquid coinjection can be obtained when the single injection volumes of deoxidized air and foam liquid are 0.1 time pore volume.The optimal parameters according to the laboratory test include foam flooding implementation when the water cut is 70%,alternate liquid-gas injection,0.1 time PV injection in a single treatment.After field parameter adjustment,the daily oil increment of test zone is 42 t/d,the water cut is reduced by 28 percentage points,the cumulative oil increment is 1.4×10⁴t,and the water production is reduced by 2.65×10⁴m³.Field test shows a favorable feasibility for the deoxidized air foam flooding program,which could provide certain technical reference for the large-scale development of Lukeqin heavy oil reservoir.

Drilling & Production Engineering

Lateral Length Limit of Ultra-long Horizontal Well in Jimsar Shale Oil Reservoir

Shi Jiangang, Xi Chuanming, Xiong Chao, Wu Jiwei, Yang Hu

2020, 27(4):  136-142.  DOI: 10.3969/j.issn.1006-6535.2020.04.021

Asbtract ( )   PDF (1486KB) ( )  

References | Related Articles | Metrics

Shale oil and gas development practices have shown that longer lateral length of horizontal well is favorable to enhance single-well controlled reserve and economic benefits. Comparing with the reservoir properties in the United States, the shale oil and gas reservoir burial depth in China is similar, but the lateral length of horizontal well is quite shorter. Drilling technology optimization and enhancing lateral length of horizontal well have become one of the technical difficulties in the unconventional hydrocarbon reservoirs in China at present. The key constraints for lateral length were analyzed by taking the ultra-long horizontal well in Jimsar shale oil reservoir as an example, including rated pump pressure, drilling fluid safety density window, drill string and casing buckling, etc. In addition, a pipe string friction-torque calculation model was derived for horizontal well. The wellbore trajectory and drilling tool combination were optimized and the technical conditions for avoiding drill-string and case buckling were researched based on the geology conditions of Well JHW00421 in Jimsar shale oil reservoir and the technical parameters of available drilling equipment. A drilling program was developed for a horizontal well with 3 500 m lateral length. The final measured depth of this well is 5 830 m and the lateral length is 3 100 m, which meet the drilling program design. This technology could provide certain technical reference for the implementation of ultra-long horizontal well in shale oil reservoir.

Test and Analysis of Mechanical Properties and Failure Patterns for the Deep Brittle Shale Under Complex Load

Fan Yu, Wang Jiajun, Liu Houbin, Wu Pengcheng, Gao Dewei, Wang Xudong

2020, 27(4):  143-148.  DOI: 10.3969/j.issn.1006-6535.2020.04.022

Asbtract ( )   PDF (1981KB) ( )  

References | Related Articles | Metrics

The deep shale in Zigong, Luzhou and other regions of Sichuan Province are characterized by high hardness, strong brittleness and well-developed bedding fractures, which results in frequent downhole stuck, overflow and other accidents during horizontal well drilling. The drilling fluid plugging performance and mechanical property tests under different confining pressure unloading rates were conducted for the deep brittle shale to clarify the effects of drilling fluid plugging performance and tripping out speed on the mechanical properties of brittle shale and the failure patterns. The test indicates that the drilling fluid plugging performance shows a significant effect on the strength and elastic modulus. The compressive strength and elastic modulus can reach 350 MPa and 16 000 MPa respectively with favorable drilling fluid plugging performance. The compressive strength and elastic modulus are only 40 MPa and 6 000 MPa respectively in case of poor drilling fluid plugging performance. The brittle shale is more likely to be failure under high confining pressure unloading rate. High tripping out speed will result in a sharp decrease of downhole effective liquid column pressure, which will lead to sidewall rock collapse. The shale failure always along the bedding fracture under bottom-hole pressure. This research reveals the mechanical properties and failure patterns of deep brittle shale under complex conditions, which could provide a scientific reference for formulating anti-collapse countermeasures.

Development and Test of Concentric Dual-tube ZonalGas Injection String in Fire-Flooding

Leng Bing

2020, 27(4):  149-155.  DOI: 10.3969/j.issn.1006-6535.2020.04.023

Asbtract ( )   PDF (1893KB) ( )  

References | Related Articles | Metrics

The development of a fire flooding concentric dual-tube zonal gas injection string was conducted to improve the failures of sealing and zonal gas injection sliding sleeve under frequent conversion between high temperature and normal temperature for the zonal fire flooding gas injection string. A concentric dual-tube string was adopted in the zonal gas injection to establish the inner and outer gas injection channels in different stages by using a fusible valve core and a fusible backing ring. A high resilience and high temperature resistant sealing rubber cylinder was used in zonal sealing, which is characterized by reliable sealing performance and convenient operation. It had been successfully applied for 2 well-times in field zonal fire flooding treatment. This technology could effective improve the sealing performance and the front profile and enhance the swept volume in zonal fire flooding treatment, which is worthy of wide promotion.

Research and Application of Dynamic Gas Well Cementing Performance Simulation within Narrow Density Window in Deep-Water Reservoir

Wu Bin, Yang Huanqiang, Wang Zhujun

2020, 27(4):  156-162.  DOI: 10.3969/j.issn.1006-6535.2020.04.024

Asbtract ( )   PDF (2217KB) ( )  

References | Related Articles | Metrics

In order to improve the large wellbore temperature difference, narrow density window and other complex problems for the cementing process in the western South China Sea Oilfield, a dynamic cementing model was established by considering the effects of temperature and pressure on cementing fluid density and rheology. The actual flow rate calculation was gained according to the transient acceleration method. The equivalent circulation density of weak points in various wellbore sections and the dynamic well parameters in each stage during the cementing process were calculated based on logging data, wellbore casing program, cementing slurry performance parameters, cementing operation parameters, etc. The technical measures for improving the gas well cementing operation safety and efficiency with narrow density window in deep-water reservoir were proposed, including reasonable design of slurry column structure, displacing with variable displacement, whole simulation process of cementing slurry injection, etc. Field application indicates that the above technical measures can effectively improve the cementing operation with large temperature difference and narrow density window. This research could provide certain guidance for the cementing operation in the western South China Sea Oilfield.

Acoustic Direct-Reading Monitoring Technology of Bottomhole Temperature and Pressure in High Temperature Well

Song Zhijun, Wang Hong, Zhang Ming, Zhang Chenjian, Zhang Mingbo

2020, 27(4):  163-167.  DOI: 10.3969/j.issn.1006-6535.2020.04.025

Asbtract ( )   PDF (1490KB) ( )  

References | Related Articles | Metrics

With the wide application of steam flooding, SAGD and fire-flooding in heavy oil reservoir, the bottomhole temperature of oil production wells gradually increases, and the maximum temperature could reach 260 ℃, which greatly limits the long-term bottomhole temperature and pressure direct reading monitoring with available cables and high temperature testing instruments. A acoustic direct reading monitoring technology of bottomhole temperature and pressure was developed by encoding the bottomhole temperature and pressure data. Acoustic transmission was adopted to transmits the signal to wellhead through production string. The wellhead signal collector receives the signal and obtains the bottomhole temperature and pressure data by decoding and calculation. 5 wells application indicate that the recorded temperature and pressure data on the surface are consistent with that stored in the instrument, which could also provide certain real-time guidance for the well production system adjustment. This technology realizes the long-term temperature and pressure direct reading monitoring in heavy oil well with thermal recovery treatment and could provide certain guidance for the well production performance analysis and production system adjustment, which can significantly improve the well production performance.

Shale Gas Wellbore Liquid Loading Identification Based on Triangle Plate

Luo Xin, Wang Yuting, Wang Xueqiang, Zhao Guojun, Chen Man, Zeng Linjuan, Yang Hai, Yan Changhui

2020, 27(4):  168-174.  DOI: 10.3969/j.issn.1006-6535.2020.04.026

Asbtract ( )   PDF (1692KB) ( )  

References | Related Articles | Metrics

In order to improve the productivity decline, insufficient liquid-carrying capacity, serious wellbore liquid loading, low recovery and other problems in the middle-late stage for the most gas wells in the Wellblock CN201 of shale gas field in Sichuan Basin, the actual production data were normalized and extremalized to eliminate the influence of parameter unit and magnitude order by comprehensively considering wellbore pressure, daily gas production and water-gas ratio according to the production performances. A triangle plate was given to analyze the scattered point distribution and determine the wellbore liquid loading area. Result indicates that the shale gas wellbore liquid loading zones for the Wellblock CN201 includes the wellhead pressure proportion is 42.38%～76.39%, the daily gas production proportion is 0.0～51.5% and the water-gas ratio proportion is 0.0～52.7%. Flowing pressure test indicates a accuracy of 84.3% for this triangle plate, which is highly reliable to identify shale gas wellbore liquid loading. This research could provide certain theoretical reference for determining on-site liquid discharge timing, liquid discharge process and liquid discharge performance evaluation.