ABSTRACTS

Vol.32 No.6, Nov. 2018

01 Reanalysis of sedimentary facies types of Carboniferous Taiyuan formation in Daniudi gas field

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

Based on the analysis of regional geological background, the sedimentary characteristics of Taiyuan formation of Carboniferous system in Daniudi gas field are analyzed. The results indicate the sandstone of Taiyuan formation has the microcosmic characteristics of high quartz grain content and good separation. The macroscopic distribution has the strip spreading point of relatively straight, narrow width and relatively large thickness characteristics. The reservoirs in the Taiyuan formation developed longitudinal cross-bedding,feather-like cross-bedding, ‘one-way’ flow structure,vein-like bedding, wavy bedding and lenticular bedding,etc., which were formed by typical tidal action. Combined with the reservoir rock particle size analysis and well logging facies analysis, it can be identified that the shallow grey, grey-white massive bedding quartz sandstone facies, light gray cross-bedding quartz sandstone facies, gray wavy bedding fine, siltstone facies and dark gray microcrystalline limestone facies.According to the analysis of the same type of rock facies,Taiyuan formation is deposited in tidal flat facies intertidal zone, and develops microfacies, such as tidal channel, tidal creek, tidal pool, mud flat and mud swamp.The favorable reservoir is tidal channel and tidal gully sandstone.

Key words: Daniudi gas field; Taiyuan formation;sedimentary facies; tidal bedding; tidal channel

06 Sedimentary characteristics and the significance of oil and gas exploration of the outcrop of the Jurassic in the Wudun sag

CAO Liwei (Exploration & Development Research Institute of Shengli Oilfield Company, SINOPEC,Dongying, Shandong 257015)

The outcrop development characteristics of lower Jurassic on the periphery of the Wudun sag in Dunhuang basin are of great significance for the analysis of the material source system and the division of sedimentary facies. The measurements of the field outcrop show that the outcrops of Jurassic are alluvial fan, fan delta, sublacustrine fan, shallow to semi-deep lacustrine facies sediments under the influence of tectonic conditions,paleoclimate and source, mainly exposed fan delta facies,sub-lacustrine fan facies deposition, the granularity of the sediment changes rapidly in vertical direction. In the early Jurassic, the sedimentation of the Dashankou formation was controlled by the boundary fault of Sanwei mountain. In the early stage, the alluvial fan-fan delta was deposited, and the deposition rate was fast. In the middle and late stage, the lake plane continued to rise, and the sediment particle became fine, and the fan-deltaiclacustrine facies developed. Sanwei mountain extruded and uplifted in the late Yanshan and strike-slip extrusion in the Xishan stage, causing the alluvial fan and fan-delta plain facies of the Dashankou formation to surface. The wedge-like sand or the turbidite sandstone reservoir and the semi-deep lake facies hydrocarbon source rock of the front of the fan delta in the sag belt of the Wudun sag are vertical stacking and transverse superimposition, they are the potential oil-gas-rich regions and have great exploration potential.

Key words: Wudun sag; Jurassic outcrop; fan delta;sub-lacustrine fan; sedimentary characteristics

12 Preliminary study on the internal structure identification technology of Proterozoic oil and gas reservoirs in Damintun sag

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

The inner Proterozoic interior reservoir is a key area for pre-exploratory discovery of Liaohe depression, there mainly developed three types of dolomites, quartzites and argillaceous rocks with different characteristics in the Proterozoic. It can be divided into 18 substrata, even substrata are dolomite reservoirs, and odd substrata are interlayers. The inner Proterozoic reservoir has the characteristics of small formation control and high point enrichment and the exploration focuses on the characterization of internal structure. Three point method and dip angle can be used to determine the occurrence of small layers, to determine the internal structure by seismic data, and to determine the internal characteristics by logging and other attributes.

Key words: Damintun sag; the inner Proterozoic reservoir; reservoir-seal assemblages; marine sediments

16 Study on reservoir configuration of large thick reservoirs in Bohai A oilfield

LIU Yujuan et al (Tianjin Company, CNOOC (China)Co., Ltd., Tianjin 300452)

By taking the large thick reservoirs in Bohai A oilfield as the research object, making full use of core,drilling, logging, seismic and dynamic data, with the hierarchical interface analysis method, the configuration study of large thick sedimentary reservoirs in braided river delta was carried out, which divided the sedimentary reservoirs of the main intervals into four or five levels on interfacial configuration units, namely underwater distributary channel, channel margin, mouth bar, sheet sand and interdistributary bay. The single sand body boundary is identified by comprehensive use of such signs as number difference of interlayer, change of sand body transverse thickness, mud deposition between sand bodies, and curve shape difference. The plane and profile configurations of single sand body and the spatial distribution of sand body are determined. The study results have been applied to the fine optimization of water injection and the exploitation of remaining oil, and good results have been achieved.

Key words: Bohai A oilfield; reservoirs;configuration study; mono sand-body molding

25 Sequence stratigraphy and sedimentary evolution characteristics of Qing 1 member in Yaoyingtai area of Changling sag

SHAO Zhifang (Exploration & Development Research Institute of Henan Oilfield Company, SINOPEC,Zhengzhou, Henan 45000)

By using the core, drilling, logging and seismic data,the strata of Qing 1 member in Yaoyingtai area, the stratigraphic sequence were divided into sequences, the isochronous stratigraphic framework with high accuracy quasi-sequence was established. and the Qing 1 member was divided into a tertiary sequence. According to the lithology of the stratum and the variation characteristics of the logging curve in vertical direction, five quasistratigraphic sequences (sand groups) were divided internally, and two kinds of quasi-stratigraphic sequences (progradation and retrogradation) were developed. In this paper, the composition, evolution and distribution of sedimentary facies in Qing 1 member are analyzed by taking the high precision quasi-sequence(sand group) as the research unit.

Key words: Changling sag; Yaoyingtai area; Qing 1 member; stratigraphic sequence; sedimentary system

33 Reservoir configuration analysis of Ed3reservoir in fault block 3 in Tangjiahe oilfield

WU Jia et al (No.1 Mud Logging Company, Bohai Downhole Drilling Corporation, PetroChina, Tianjin 300280)

In order to make clear the distribution characteristics of the residual oil in Tangjiahe oilfield, by taking Ed3reservoir in fault block 3 as an example, on the basis of data analysis on core, logging, seismic and dynamic information, the internal configuration model of the single sand body in the mouth bar was established, the identification marks and spatial distribution characteristics of the internal structural units of reservoirs in the mouth bar were discussed, and the threedimensional configuration model of the sand body was established. The results show that the sand body of Ed3reservoir in fault block 3 in Tangjiahe oilfield is in the shape of flowers or bands, with an average thickness of 4.5～6.7 m and an average width of 400～1 000 m. Mud interlayers are developed inside the mouth bar, with the interlayer thickness generally less than 2 m. Vertically,the dam body is mostly separated by relatively stable mud interlayers, and the configuration interface of the single sand body controls the distribution of oil and gas. In the lateral direction, the sand bodies of a single dam are unconnected mudstone interlayer, weakly connected dam edge contact and connected main dam superposition.

Key words: Tangjiashan oilfield; reservoir configuration of mouth bar; residual oil distribution

37 Geochemical characteristics of Ordovician crude oil in the No. 1 fault zone of Shunbei oilfield

GAO Xiaoge et al (Yangtze University, Jingzhou,Hubei 434023)

Through the analysis of the basic physical properties and geochemical characteristics of crude oil，combined with the drilling data, producing data and temperaturepressure testing data, the geochemical characteristics and hydrocarbon accumulation model of lower-middle Ordovician in No. 1 fault zone of Shunbei oilfield were studied. The results indicate the No. 1 fault zone of Shunbei oilfield is an unsaturated volatile reservoir with high gas-oil ratio and it was formed in the partial strong reduction sedimentary environment. The crude oil belongs to the marine crude oil which was formed by the evolution of the aprotic typeⅠ kerogen. The marine crude oil generated is in the stage of high evolution and maturity. The biomarker of crude oil is similar to the black shale of Yultus, which is derived from Cambrian source rock. The migration path of oil and gas is dominated by vertical migration and the fracture is the main migration channel.

Key words: Shunbei oilfield; Ordovician crude oil;high-mature; vertical migration

41 Preservation conditions analysis of hydrocarbon in Kurdish region of Iraq

ZHOU Hanghui et al (Sinopec International Exploration and Production Corporation, Beijing 100029)

Based on the analysis of the tectonic evolution and the hydrocarbon accumulation types and distribution characteristics, the preservation conditions of oil and gas reservoirs in Kurdish region of Iraq were studied. The results showed that the oil generation period in Kurdish region was slightly earlier than the trap formation period,oil and gas filling was in the trap formation period, and the fault sealing was still active. After oil and gas accumulation, the tectonic movement continues to transform the oil and gas reservoir, which will damage the oil and gas conservation. Atmospheric fresh water infiltrates into the reservoir and the oxidation makes the density of crude oil increase. The hydrocarbon accumulation was controlled by the preservation condition of hydrocarbon in Kurdish region.

Key words: Kurdish region; hydrocarbon exploration;accumulation characteristics; preservation conditions

45 Fracture formation in Paleogene-Neogene sedimentary rocks of Zhanhua sag

MEN Jingxuan et al (Key Laboratory Continental Dynamics, Department of Geology, Northwest University,Xi'an, Shaanxi 710069)

Fracture is a good hydrocarbon reservoir space and migration channel, but there is little research on the difference of fracture strength among different rocks that affect the formation of fractures. Based on core observation and thin section analysis, the fractures in the Paleogene-Neogene of Zhanhua sag were classified. By using triaxial rock mechanics test, the rock fracture strength was compared and analyzed. The results show that the fracture is mostly developed at the interbed interface of different lithologies. Under the action of vertical pressure, the fracture strength is successively carbonate, mudstone and sandstone.

Key words: Zhanhua sag; fracture type; lithologic combination; triaxial stress test

52 Sand and gravel reservoirs prediction techniques and methods of the southern steep slope zone in Biyang sag

BU Xuqiang (Exploration & Development Research Institute of Henan Oilfield Company, SINOPEC,Zhengzhou, Henan 45000)

Restricted by the spread range of the drilled sandgravel rock body, the study of source supply channel of sand-gravel rock body was controlled by the fault transition zone, the determination of sand-gravel body by seismic phase analysis, and the prediction of sand-gravel mass by attribute analysis. The results show that the fault position control of the transformation zone supply channels, the gravel rock source affected the paleogeomorphic form, thus forming a groove corresponding sedimentary framework, and the chaotic properties can describe the distribution range of gravel rock. The faster the sand and gravel mass accumulation, the worse the stratification, the more chaotic the seismic reflection and the higher the value of chaotic property.

Key words: Biyang sag; fault transition zone; gravel reservoir; chaotic property

59 Comprehensive quantitative evaluation on reservoirs of Kela 2 gas field in Tarim basin

XU Yanmei et al (Exploration & Development Research Institute, PetroChina, Beijing 100083)

In order to solve the problem of contradictory evaluation indexes in the process of qualitative evaluation of Kela 2 gas field in Tarim basin, the weight coefficient of evaluation indexes was determined by grey relational analysis, the comprehensive evaluation index of the reservoir was calculated. The comprehensive quantitative evaluation of the reservoirs in the Baskichik formation in the trap was carried out, the results of reservoir classification were given, and the reservoir evaluation results were verified by using the productivity data. The results show that the coincidence rate of the quantitative classification of the first reservoir of Baskichik formation is 87%, and the coincidence rate of the second reservoir of baskichik formation is 85%. The classification results are reliable and can provide the basis for decisionmaking of gas field development.

Key words: Kela 2 gas field; Baskichik formation;grey relation grade analysis; quantitative evaluation on reservoirs; reservoir classification

64 Application of risk probability method in oil and gas block evaluation

CHEN Xiaomei et al (Exploration & Development Research Institute of Southwest Oil and Gas Company,SINOPEC, Chengdu, Sichuan 610041)

How to scientifically evaluate the oil and gas block and achieve the block orderly advance and retreat is the key point of the mining rights work. The previous block evaluation was to put blocks with different exploration levels on the same platform for evaluation, and the evaluation results were limited, while the evaluation of oil and gas blocks by using the risk probability method could obtain scientific results. According to different exploration degrees, the blocks are classified to calculate the exploration degree index. Different oil and gas geological evaluation parameters are used for the blocks with different exploration degrees. The exploration value of oil and gas blocks is evaluated according to the results of resource evaluation. Finally, according to exploration degree index, probability of containing oil and gas and exploration value, the expert opinion method is adopted to conduct comprehensive optimization and queuing, and then the evaluation results of oil and gas blocks are given,which can provide a good reference for exploration deployment decision.

Key words: block evaluation; risk probability method; exploration degree index; hydrocarbon-bearing probability

67 Study on recovery factor and its influencing factors of small layers in commingling production gas field

REN Qianying1 et al (College of Petroleum Engineering, China University of Petroleum (Beijing),Beijing 102249)

Interlayer production imbalance existed in commingling production of Jingbian gas field, it is of great significance to make clear the recovery factor status of interlayer recovery and the influencing factors of recovery factor for balanced production, potential tapping adjustment and enhanced recovery factor of gas field.Taking well area A of Jingbian gas field as an example, by using drilling, logging interpretation and production performance data, based on the calculation of geological reserves and dynamic reserves, dynamic reserves analysis method and correlation analysis technology are used to study the interlayer recovery factor and its influencing factors. The results show that the recovery ratio of small layers varies greatly under the condition of multi-layer commingled production in Jingbian gas field. The recovery factor of the small layers shows a pattern of one high and the rest low, and the recovery factor of small layers is mainly controlled by reservoir physical properties, especially permeability, but not closely related to effective thickness and gas saturation.

Key words: Jingbian gas field; commingling production; interlayer recovery

70 Study on predicting the recovery efficiency of low permeability gas reservoirs

MU Zhongqi et al (College of Petroleum Engineering,China University of Petroleum (Beijing), Beijing 102249)

Low permeability gas reservoir is particularly low in permeability and strong in heterogeneity, which easily causes the extremely uneven employment of the whole gas reservoir during development and brings inconvenience to the calculation of recovery. In order to propose a method more suited to low permeability gas reservoirs for calculating the recovery, the strategy that calculate each production well separately was adopted in consideration of the disequilibrium of employment, then a method for predicting the recovery of low permeability gas reservoir under the existing well pattern was proposed, which was based on break-even analysis, theory of vertical pipe flow in gas well, deliverability equation and material balance equation. The S area in Jingbian gas field was taken as an example of calculating the recovery and the result was 49.4%, which was obviously lower than that of middlehigh permeability dry gas reservoir.

Key words: Jingbian gas field; low permeability gas reservoir; recoverable reserve; recovery efficiency

73 Establishment and application of the curve relation chart between water content and recovery degree of water flooding reservoir in Bohai oilfield

ZHAGN Hongyou et al (Tianjin Company, CNOOC(China) Co., Ltd., Tianjin 300459)

According to different oil viscosity, the water flooding reservoir in Bohai oilfield is divided into low viscosity, medium and high viscosity, normal heavy oil(grade I-1) and normal heavy oil (grade I-2). Aiming at different types of water flooding reservoirs, typical development units are selected to calculate the actual curve of the relation between water content and recovery degree, and the normalization process is carried out. By using Wanjiye water flooding curve for quantitative fitting,the curve chart of relation between water content and recovery degree of different types of water drive reservoirs is established to reflect the difference of increasing regularity of water content in different types of water flooding reservoirs. The relation chart has been successfully applied to the evaluation of development effect of nearly 50 water flooding reservoirs in Bohai oilfield and the evaluation results are objective and accurate, which can truly reflect the actual development level.

Key words: Bohai oilfield; water flooding reservoir;water content; recovery degree; relation chart; Wanjiye water flooding curve

89 Experimental analysis of stress sensitivity of low permeability gas reservoir

ZHANG Xiaolong et al (Shanghai Company,CNOOC (China) Co., Ltd., Shanghai 200335)

In order to study the influence of formation pressure change on permeability and porosity of low permeability reservoir, the conventional stress sensitivity experiment and simulated stress sensitivity experiment caused by formation pressure drop during gas reservoir development were carried out respectively. The experimental results show that the relationship between effective stress and porosity and permeability is a power form, and the stress sensitivity of permeability is stronger than that of porosity.Water saturation has great influence on the stress sensitivity of permeability. Under the same net stress, the gas permeability decreases with the increase of water saturation.

Key words: low permeability gas reservoir; stress sensitivity; effective stress; experimental analysis

99 Study and application of fracturing transformation technique for tight gas reservoir in Sulige gas field

YANG Zhanwei et al (Exploration & Development Research Institute, PetroChina, Langfang, Hebei 065007)

As the productivity of tight sandstone gas reservoir in Sulige gas field after fracturing is not ideal, the difficulty on the transformation of low-pressure tight gas reservoir was analyzed, the capacity seepage model and capacity equation after transformation were established,the key factors of influencing the production after transformation were analyzed, and the production of two wells under different fracturing effect was compared. The results show that the tight gas reservoir fracturing of formation damage includes the damage caused by fracturing fluid itself and construction flowback technology, and the fracturing fluid flowback time impact on the low-pressure gas reservoir damage is bigger. The fracturing fluid with no residue and clean with low damage, and the quick-flowback technique after fracturing are the keys to improve the effect of lowpressure tight gas transformation.

Key words: Sulige gas field; tight gas reservoir;fracturing transformation; seepage flow model

106 Pilot test and application of pressure boosting and injection increasing technology in Bohai oilfield

ZOU Dehao et al (Tianjin Company, CNOOC (China)Co., Ltd., Tianjin 300459)

Shortly after the injection of some injection wells in Bohai oilfield, the injection pressure quickly rose to the maximum injection pressure of the overall development plan, and the water injection could not meet the reservoir injection demand, which seriously affected the development effect of the oilfield. In this regard, the study on pilot test of pressure boosting and injection increasing,and the study of pressure drop funnel were carried out for the first time, which has determined the feasibility and reliability of the pressure boosting and injection increasing technology and has been applied in Kenli K oil field. By increasing the injection pressure at the wellhead,the small layer with higher start-up pressure starts to absorb water, the daily injection amount of the injection well increases obviously, effectively increasing the reserves for water drive, which plays an important role in improving oil recovery.

Key words: Bohai oilfield; water injection pressure;fracture pressure; pressure boosting and injection increasing

109 Parameter optimization and numerical simulation analysis of varied perforated premium screens in horizontal wells

CHEN Yang (Drilling Technology Research Institute of Shengli Petroleum Engineering Co., LTD,SINOPEC, Dongying, Shandong 257017)

Aiming at the problem that the control effect is not ideal due to the design of flowing control completion parameters of horizontal wells with varied perforated premium screen on the basis of field experience, a corresponding optimization method for completion parameters is preliminarily established. According to the reasonable additional pressure drop requirements calculated by numerical model, the optimal control parameters were selected to control the discharge intensity of each well section in a reasonable range, and the equilibrium liquid supply was achieved. A case study shows that compared with conventional sand control completion method, the optimal design brings 9.69%more cumulative oil and 10.68% less water content on the 300 th day after well opening, while the experiential design only 2.13% more oil and 2.99% less water, which indicates the enhanced capacity of water control and stable oil production of the optimal design.

Key words: horizontal well; flowing control completion; varied perforated premium screens;parameter optimization; numerical simulation