Lithologic Reservoirs

Referring to the previous research achievements, guiding by theories of seismic stratigraphy and modern hydrocarbon accumulation, this paper put forward a new kind of unconformity type classification scheme on the basis of the profile morphology and the combination of seismic reflection end of two sides of the unconformity surface. In this scheme, the unconformity was divided into six kinds of types: parallel-fold type, parallel-truncation type, parallel parallel type, onlap-fold type, onlap-truncation type and onlap-parallel type. Among them, the upper part of parallel-fold type and parallel-truncation type are favorable for hydrocarbon migration, and the lower part are favorable for hydrocarbon accumulation; the upper or lower part of parallel-parallel type are favorable for hydrocarbon migration and favorable for hydrocarbon accumulation under the match of fault and fold; the upper or lower part of onlap-fold type and onlap-truncation type are most favorable for hydrocarbon accumulation; the upper part of onlap-parallel type are favorable for hydrocarbon accumulation, and the lower part are favorable for hydrocarbon migration. This classification scheme is more efficient and applicable because of considering unconformity as a whole and the relationship between unconformity and hydrocarbon accumulation, which will be favorable for stratigraphic reservoir exploration.

Reservoir characteristics and controlling factors of Wenchang Formation in Xijiang-Huizhou transform zone, Huizhou Sag

CHEN Shuhui， ZHANG Xiaoyu

2013, Vol.25(6): 8–14 Abstract ( 740 ) PDF (505 KB) ( 322 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.002

The reservoir of Wenchang Formation in Huizhou Sag is the key exploration strata of Paleogene in Pearl River Mouth Basin. Based on the data of thin section, scanning electron microscope and properties, this paper studied the petrologic characteristics, reservoir space, pore structure, properties and main controlling factors of the reservoir of Wenchang Formation in Xijiang-Huizhou transform zone. The result shows that pore types are mainly intergranular corrosion expansion pores and primary intergranular pores, and a great deal of kaolinite was precipitated in corrosion pores and primary pores and produce intercrystalline pores in some strata. The pore structure is better in the reservoir which the intercrystalline pores are not developed. The content of clay, carbonate and feldspar in the fillings are the main controlling factors. The crush fracture formed by compaction is the major contribution to the permeability of deep reservoir. The clay film of the illite-smectite mixed layer which is formed early can resist the compaction and inhibit the corrosion on the grain, preserving some intergranular pores.

Sedimentary facies of the lower Lulehe Formation in Qie 16 well block of Kunbei Oilfield

MO Fengyang， MU Zhonghai， CHANG Lin， YOU Chao， XU Le

2013, Vol.25(6): 14–19 Abstract ( 559 ) PDF (768 KB) ( 427 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.003

Based on the regional geologic backgrounds, combined with core features and well logging data, this paper studied the facies of the lower Lulehe Formation in Qie 16 well block of Kunbei Oilfield by systemic analysis of the lithologic characteristics, structures and logging interpretation. The alluvial fan was developed in the target stratum, which could be further divided into two sub-facies of top-fan and middle-fan, and six microfacies of mud-rock flow, stream ditch, ditch beach, braided stream line, braided stream sand island and overflow belt. The distribution characteristics of facies were revealed by the lithologic column and plane distribution diagram of facies about single well. The target stratum shows the features of retrogradation alluvial fan. The depositional pattern was built up and the favorable microfacies belt was evaluated, which provides theory foundation for the further exploration and development in the target stratum of Qie 16 well block.

Analysis of influencing factors of early productivity of Chang 10 reservoir in Ansai Oilfield

LI Tao， ZHANG Huaiguang， QU Chunxia， YANG Weiguo

2013, Vol.25(6): 20–24 Abstract ( 496 ) PDF (585 KB) ( 302 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.004

Based on the analysis of the early productivity distribution of Chang 10 reservoir in G52 well field of Ansai Oilfield, this paper analyzed the influence of sedimentary microfacies and diagenesis（diagenetic facies） on the early productivity. The result shows that the early productivity distribution is closely related to sedimentary microfacies. Distributarychannel has a higher earlyproductivityfor the precession ofthick sand beds, thick oil reservoirs, relatively high porosityand permeability, whereas the channel edge has a lower earlyproductivitybecause ofits opposite features against the distributary channel. The early productivity is subjected to the effect of diagenesis（diagenetic facies）. For the decline of reservoir properties, the early productivity of strong corrosion lithofacies reservoirs, corrosion lithofacies reservoirs and corrosion-chlorite cementation lithofacies reservoirs reveals the same trend. Gradual intensity of the destructive diagenesis heading southwest resulted in poor reservoir properties and thus accounts for rather lowor even noearlyproductivity.

Characteristics of tight sandstone reservoir of Chang ₄₊₅ oil reservoir setin Yan’an area, Ordos Basin

YANG Jie

2013, Vol.25(6): 25–29 Abstract ( 700 ) PDF (495 KB) ( 549 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.005

According to the data of rock thin section, cast thin section, scanning electron microscope, X diffraction of clay minerals, high pressure mercury and properties analysis, this paper studied the characteristics of tight sandstone reservoir of Chang 4+5 oil reservoir set in Yan’an area. The results show that the rock type of Chang 4+5 sandstone reservoir is mainly fine-grained feldspar sandstone; porosity and permeability range from 6.0% to 10.0% and 0.2 mD to 2.0 mD respectively, and the reservoir belongs to typical tight sandstone reservoir; reservoir space is mainly residual intergranular pores, followed by dissolved pores in feldspar and laumontite; pore structure is dominated by small pore and fine throat type, followed by fine throat and pore tiny throat type; compaction and cementation in chlorite, calcite and laumontite are the main factor for causing poor reservoir properties, and dissolution improves reservoir properties. The results of this study provide a geological basis for rolling exploration and development for Chang 4+5 oil reservoir set in Yan’an area.

Model and technologies of subtle traps identification in irregular geologic body: An example of fan body traps

LUO Qun， WANG Chongxiao， TANG Min， HUANG Handong

2013, Vol.25(6): 30–34 Abstract ( 609 ) PDF (665 KB) ( 404 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.006

It is difficult to effectively forecast irregular geologic body by using common geophysical techniques because of its strong elusive features and great difficulties on identification. Seismic sedimentology and geophysical techniques provide favorable theory guidance and technical support for effectively forecasting subtle traps in irregular geologic body. Setting up correlative relationship among seismic attributes, sedimentary facies and subtle traps is the basis for effectively identifying subtle traps, and seismic facies analysis, wavelet frequency-division, facies controlling inversion are the key techniques. The prediction and exploration of fan body traps of lower Sha 3 member in Che 15 well field in Chezhen Sag show that the model of “integration of seismic and geologic, integration of theory and techniques” for subtle traps identifyication has greater application value.

New methods for the exploration, evaluation and development of unconventional reservoirs

WANG Tuo， ZHU Rukai， BAI Bin， WU Songtao

2013, Vol.25(6): 35–39 Abstract ( 535 ) PDF (800 KB) ( 859 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.007

Unconventional petroleum especially shale oil and gas have great geological reserves and large exploitation potentiality, and petroleum in shale reservoir has achieved industrialized production in North America. Because of the properties of low permeability and low porosity compared with conventional reservoir, new geological methods and advanced technologies should be employed for unconventional reservoir research. Based on the studyofshale reservoir in Eagle Ford, Marcellus and Hawkville, this paper proposed a series ofnewapproaches for exploration, evaluation and development ofunconventional reservoir. Firstly, 2Dand 3Dseismic alongwith pilot well used toidentifyconfiguration and the boundary of the target basin, as well as the thickness and area of reservoirs. And then, core data were used to carryout logcalibration soas toacquire comprehensive loggingcurve interpretation includingloggingdata, petrophysical analysis data and seven properties of shale reservoirs. Combined with seismic identification technology, “sweet spot” and favorable reservoirs distribution were effectivelypredicted. Finally, geosteeringwas applied toallowthe well tostay within the target windowin reservoir, and combined with 3Dseismic technology, designed scheme ofhydraulic fracture stimulation for different geologic reservoirs. The successfullyexploration ofthese newmethods can provide reference for the exploration, evaluation and development oftight oil/gas, shale oil/gas and coalbed methane in China.

Pore structure evaluation of low permeability reservoir based on pore fractal features

ZHANG Xianguo，ZHANG Tao, LIN Chengyan

2013, Vol.25(6): 40–45 Abstract ( 770 ) PDF (525 KB) ( 613 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.008

Pore structure is an important factor that influences percolation capacity and oil production of low permeability reservoir. It is a hot spot in low permeability reservoir study. A quantitative method for pore structure evaluation which can characterize pore structure of heterogeneous reservoir on macro-scale is needed. Taking low permeability reservoir of Cretaceous in Tanan Depression as an example, based on thin slices observation, porosity and permeability test and capillary pressure test, this paper applied fractal algorism to reservoir pore structure evaluation, and established a quantitative pore structure evaluation method based on pore fractal dimension from mercury intrusion test. The result shows that there are four types of pore structures developed in the study area, including coarse shape type, subcoarse shape type, subfine shape type and fine shape type. Pore fractal dimension can be calculated according to the linear relationship between logarithm of capillary pressure and logarithm of wetting phase saturation. The smaller the pore fractal dimension is, the better the pore structure will be. The pore fractal dimension criteria for pore structures classification was built up with thin slice and oil testing. It is also found that large pores and small pores have different fractal characters in high heterogeneous reservoirs in the study area, which performs as the segmental character in the relationship between capillary pressure and wetting phase saturation.

Characteristics and comprehensive evaluation of deep reservoirs in Qinan ramp, Qikou Sag

ZHANG Jing， LI Shuangwen， LIU Huaqing， YUAN Shuqin， NIU Haiqing， LIU Zhigang

2013, Vol.25(6): 46–52 Abstract ( 655 ) PDF (913 KB) ( 404 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.009

By analyzing thin sections, scanning electronic microscope and physical properties，this paper studied the characteristics and influencing factors of deep reservoirs in Qinan ramp of Qikou Sag. The result shows that the third member of Shahejie Formation belongs to low porosity and ultra-low permeability reservoir, there developed three secondary pore zones in the vertical direction. The development of deep secondary pores is dominated by sedimentary facies belt, dissolution and anomalous pressure, and the occurrence of fractures can reform the deep reservoir. According to the physical properties, sandstone thickness and pressure coefficient, the reservoir in the study area can be divided into four types. The reservoirs of type Ⅰ and Ⅱ have better physical properties and they are the main reservoirs to increase production in the future.

Characteristics and controlling factors of tight sandstone reservoir of the third member of Shahejie Formation in the southern West Depression, Liaohe Basin

SUN Honghua，LI Xuping，ZHONG Jianhua，FAN Wei, LIU Lei，ZHOU Jiao

2013, Vol.25(6): 53–61 Abstract ( 590 ) PDF (826 KB) ( 757 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.010

By means of observation of core samples, casting thin sections and ordinary thin sections, combined with recording, logging data, scanning electronic microscope and clay mineral X-ray diffraction analysis, this paper studied the petrology characteristics and physical properties of the tight sandstone reservoir of the third member of Shahejie Formation in the southern West Depression, and analyzed the main influencing factors for reservoir properties. The result shows that the reservoir rock is composed of tight sandstone with lowto ultra-lowporosity and lowto ultra-lowpermeability; with lithic and feldspar as its main components, the detrital grain has low compositional maturity; grain contacts are mainly line contact and point-line contact; porosity and permeability are different in the vertical and the horizontal sections of the reservoirs, and the reservoir heterogeneity is strong; the main factors that affect the reservoir properties are source, sedimentation, diagenesis, depositional systems, tectonism and abnormal pressure. The analysis of the dominant factors of the physical properties of tight sandstone reservoir can provide basis for the prediction and evaluation of high-quality tight sandstone reservoirs and exploration and development of tight sandstone gas reservoirs

Identification of Jurassic lithologic traps in Fudong slope area, eastern Junggar Basin

WANG Junhuai，WU Junjun，YIN Changxia，WU Tao，BIAN Baoli

2013, Vol.25(6): 62–66 Abstract ( 576 ) PDF (602 KB) ( 566 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.011

Based on the theory and method of seismic sedimentology, according to the channel sands of Jurassic Toutunhe Formation in Fudong slope area of Junggar Basin, this paper carried out identification of lithologic traps and investigation of new technology by comprehensive use of seismic attributes analysis technology, coherence analysis technology, frequency spectrum decomposition technology, 3D visualization and full 3D cube seismic interpretation technology. Because the characterization of lithologic target by single seismic attribute has stronger multiplicity, so multi-attributes analysis was applied to decrease multiple solutions and increase forecasting precision. By mutual verification of these multi-attributes, forecasting precision was improved and exploration risk was reduced. The channel sands of the study area were identified by using various new seismic interpretation technologies, displaying spacial distribution characteristics of sands clearly from many aspects, and many lithologic objects were identified. Through many years of exploration, lots of lithologic reservoirs were found, such as Fudong 2, Fudong 5 and Fudong 16 reservoir. This study can provide a new thinking and new exploration objects type for lithologic reservoir exploration in Junggar Basin.

Application of seismic multi-attribute optimization technology to the prediction of carbonate fractured-vuggy reservoir

HAN Changcheng， LIN Chengyan， MA Cunfei

2013, Vol.25(6): 67–70 Abstract ( 699 ) PDF (533 KB) ( 544 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.012

The carbonate fractured-vuggy reservoir is characterized by strong heterogeneity, fast lateral lithology alternation, which brings great difficulties for seismic reservoir prediction. Firstly, this paper used single seismic attribute to select seismic attributes such as time, amplitude, frequency and absorption attenuation which are corresponding with the reservoir well; secondly, carried out correlation analysis and intersection analysis of these attributes, and reserved only one type of the attributes which has high correlation degree to reduce the redundancy; and then carried out cluster analysis and grey correlation analysis between the reservoir parameters and the reserved attribute, and optimized three types of attributes including amplitude alternation, arc length and band width which have high grey correlation degree with carbonate fractured-vuggy reservoir parameters; finally, completed reservoir identification and prediction by 3D cross-plot analysis and neural network analysis.

Geologic characteristics and controlling factors of tight sand reservoir in the mid-eastern Ordos Basin

WANG Weili，GAO Hairen

2013, Vol.25(6): 71–78 Abstract ( 635 ) PDF (679 KB) ( 556 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.013

The study on the geologic characteristics and controlling factors of Permian tight sand reservoir in the Mideastern Ordos Basin is still a blank field. Based on core description, rock sample analysis and test, and diagenetic evolution analysis, this paper studied the microscopic characteristics and controlling factors of the reservoir. The results show that the capillary pressure curves in the eighth member of Shihezi Formation and the second member of Shanxi Formation are characterized by steep tilt, which indicates poor porosity（the average value of the two members is 6.14% and 4.49% respectively） and permeability（the average value of the two members is 0.389 mD and 0.749 mD respectively）. The reservoir development is controlled by depositional settings and diagenesis. The reservoirs of the eighth member of Shihezi Formation and the second member of Shanxi Formation are mainly developed in distributary channel sand bodies of the delta front subfacies and in the late diagenetic stage B, and the second member of Shanxi Formation is even in the stage C in some region. The compaction and cementation of silica, carbonate and clay mineral make the reservoir properties poor, and dissolution is constructive for reservoir properties.

Characteristics of fluid inclusion and accumulation period of Chang 9 oil reservoir set in Ansai area, Ordos Basin

ZHENG Hui，BAI Yubin，HAO Xiaorong，CAO Qing，LIU Peng

2013, Vol.25(6): 79–83 Abstract ( 565 ) PDF (429 KB) ( 489 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.014

In order to determine the hydrocarbon filling and accumulation period of Chang 9 oil reservoir set in Ansai area, based on the microscopic observation of fluid inclusion, fluorescence analysis and micro thermometry of associated saline inclusion in quartz overgrowth boundary, combined with the simulation of burial-thermal evolution history of Chang 9 oil reservoir set, the hydrocarbon migration and accumulation time were confirmed. The result shows that Chang 9 oil reservoir set mainly developed saline inclusion and liquid hydrocarbon inclusion. They mainly distributed in the overgrowth edge of quartz and its dissolved fractures, with circular and irregular forms and the size of 2～6 μm. The homogenization temperature shows unimodal distribution, and mainly ranges from100 ℃ to 110 ℃. One time of hydrocarbon charging occurred in Chang 9 oil reservoir set, corresponding to the middle and late period of Early Cretaceous ( 100～120 Ma ) in the geological history.

Prediction method for tight sand reservoir in M region

CHEN Chao，LIU Yun，MIAO Zhiwei

2013, Vol.25(6): 84–88 Abstract ( 583 ) PDF (696 KB) ( 443 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.015

Braided delta front facies is the major depositional system developed in Late Triassic Xujiahe Formation in Mregion, where deposited a large set of sandstone with mudstone thin layer. The reservoir is typical sand bag mud sedimentation and tight sandstone reservoir with very lowporosity and permeability, and porous sandstone is the main reservoir type. Therefore, howto effectively distinguish the thin mudstone layer and none-reservoir dense sandstone is very important for reservoir prediction in Mregion. This paper used gamma inversion and porosity curve fitting acoustic inversion to reflect the porous reservoir response and conduct comprehensive reservoir prediction. The result shows that the northwest ofMregion is the main streamchannel development area, where reservoir is relatively developed.

Quantitative characterization of Ordovician carbonate fracture-cavity aggregate in Tarim Basin

YANG Pengfei， ZHANG Lijuan， ZHENG Duoming， LI Guohui， LUO Haoyu， XU Lei

2013, Vol.25(6): 89–94 Abstract ( 620 ) PDF (564 KB) ( 666 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.016

Quantitative characterization of large fracture-cavity aggregate is the keymethod for efficient development of medium-low abundance fracture-cavity reservoir with fewer wells. Carbonate fracture-cavity reservoir is characterized by complex structure, multi-stage geologic origin and strong heterogeneity, which makes it difficult to develop by conventional modeling means. Taking typical block in Halahatang Oilfield in Ordos Basin as an example, combined with geologic features and seismic facies analysis, this paper used cluster analysis method to carry out geometric modeling of large fracture-cavity aggregate. Considering the lack of well logging data, complicated inner texture and strong heterogeneity of carbonate fracture-cavity reservoir, we applied geostatistical inversion technology to the reservoir lithofacies and porosity modeling, established static model of fracture-cavity aggregate for Halahatang Oilfield, and carried out the quantitative characterization. Furthermore, modified the size, boundary and connectivity of the large fracture-cavity aggregatemodel by dynamic data fromsingle well and multiple wells, and completed the fine characterization. The study result can guide the drilling site design and development.

Comparison and application of two kinds of converted wave common conversion point binning methods

YANG Wei， WANG Xiaowei， BIAN Donghui

2013, Vol.25(6): 95–97 Abstract ( 622 ) PDF (357 KB) ( 361 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.017

It is known that the conventional common midpoint binning method can not be used in converted wave processing because of the asymmetry during the converted wave propagation. Therefore, the research on converted wave common conversion point （CCP） binning method is very important. At present, asymptotic method and target-oriented method are twomain kinds of common conversion point binningmethods. Through the comparison and analysis of these two kinds ofmethods, this paper carried out common conversion point binning of converted wave data in the actual field, and compared the stack sections obtained by the two kinds ofmethods. The result shows that the target-oriented method can calculate the conversion point position of the target time or layer flexibly, which is better than asymptotic method.

Logging evaluation method of reserve parameters of carbonate gas reservoir

WANG Qingru， LI Jinggong

2013, Vol.25(6): 98–102 Abstract ( 523 ) PDF (604 KB) ( 361 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.018

Both the oil and gas reserves and production contained in carbonate oil and gas reservoir exceed half of the total oil and gas production, so it is significant to carry out study on reserve parameter evaluation of carbonate oil and gas reservoir. Carbonate reservoir is characterized by complex lithology, various types of reservoir space, markedly changed secondary pores and strong heterogeneity, which makes the porosity and permeability evaluation difficult in the reserve calculation. Taking a marine carbonate gas field as an example, based on conventional log data, this paper conducted integrated studies on dual-medium reservoirs from the aspects of lithology identification, calculation of porosity and permeability and fracture identification. The result shows that conventional log data can be used to identify the lithology and fractures of carbonate reservoir effectively, can be applied to quantitatively calculate the porosity and permeability of primary pores, dissolved shrinkage pores and fractures of dual-medium reservoir, and can be used to establish the criterion for quantitative fracture identification. This study can provide reference for the study of dual-medium reservoir when there is lack of core and image logging data.

Two-phase flow model for non-annular flow in gas wells

LIU Tong，REN Guirong，ZHAO Ronghuai

2013, Vol.25(6): 103–106 Abstract ( 535 ) PDF (365 KB) ( 476 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.019

The current two-phase flow models developed for gas wells cannot be used to correctly predict the pressure losses and micro-flow-parameters for non-annular flow in gas wells. This paper established a two-phase flow model for non-annular flow in gas wells. Firstly, a non-annular flow-pattern prediction model was proposed based on the force balance of liquid droplet and the blockage of liquid film. Then a unit-cell model for pressure drop was developed according to the intermittent flow characteristics of non-annular flow. The bubble rise velocity was obtained based on drift-flux model, and the void fraction in liquid slug was obtained from the Schmidt experimental data. The evaluation data from 38 non-annular-flow gas wells show that the relative error of this model is only -1.464%. Application examples show that the model can calculate the detailed flow parameters.

Research and application of depressurization and stimulation of injection well for ultra-low permeability oilfield

XUE Jianqiang，QIN Xiaoping，LAI Nanjun，YE Zhongbin，LI Han

2013, Vol.25(6): 107–111 Abstract ( 683 ) PDF (350 KB) ( 399 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.020

In order to reduce injection pressure and increase water injection in ultra-low permeability oilfield, a system of depressurization and stimulation of injection well was developed. It is constituted by 320～850 mg/L gemini surfactant G12-3, 60～200 mg/L antiswelling agent NNR, 16～50 mg/L inhibition agent YJ and 4～20 mg/L ferric ion stabilizer QA. The interfacial activity, antiswelling performance, inhibition ability, and reverse wetting ability of this system were investigated under various conditions. When the mass concentration of the depressurization and stimulation of injection well system solution was 400～1 200 mg/L, the interfacial tension was reduced to 10-3 mN/m, the antiswelling rate is 81.2%～89.3%, and the inhibition rate was 84.7%, 83.5% and 81.7% for Ca2+, Ba2+ and Fe3+ respectively. With the increase of mass concentration of this system, mica surface wettability turned to weak water wettability, and oil-water relative permeability curve also shows that the system could improve the flow ability of formation fluid. At last, field test shows that the system made the injection pressure of injection well T214-16 reduced about 3.5 MPa, and the term of the validity of this measure was more than 6 months. It attained good application effect in this area.

Laboratory study on micro suspension emulsion plugging agent

ZHANG Lili，XIE Gang，JU Dengfeng，XIE Juan，HAO Huijun，HAO Guoyong

2013, Vol.25(6): 112–116 Abstract ( 674 ) PDF (326 KB) ( 319 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.021

It is recognized that the normal chemical plugging agent cannot plug water and control profile effectively in formations with permeability ratio data more than three. Stable oil-in-water micro suspension emulsion （grain size 1～5 μm） was prepared from main material oil-soluble resin, emulsifier and stabilizer through disperse mill. The optimal formula was determined as follows: 50%～60% resin +0.35%～0.40% octadecyl trimethyl ammonium chloride or 0.35%～ 0.40% sodium benzenesulfonat +0.1% CMC +0.10%～0.15% calcium chloride +1%～5% SL+ water. Demulsifier formulation were also determined, 2%～3% aqueous solution of sodium hydroxide and 3%～5% calcium chloride solution were used for cationic emulsion and anionic emulsion corresponding. Viscosity, electron microscopy analysis of grain size, acid solubility, oil solubility tests were also carried out. Performance test shows that it has high temperature range and good injection and selectivity performance. Core flooding test shows that the breakthrough pressure gradient was 26 MPa/m, the plugging rate is greater than 97%, it kept high plugging rate after large amount of water flooding and it had good profile control performance for heterogeneous reservoir with the permeability ratio data being of seven.

Productivity prediction and main layer optimization for composite reservoir

CHENG Liangbing， YANG Jun， FENG Shunyan， DING Li， MA Jing

2013, Vol.25(6): 117–121 Abstract ( 605 ) PDF (538 KB) ( 466 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.022

There are many factors affected the production of low permeability reservoir, among which the reservoir pore space, permeability and oiliness are the main factors. Taking H195 well field as an example, through correlation analysis of logging parameters and initial productivity, this paper obtained the main logging parameters that can reflect the reservoir characteristics, and established productivity prediction models of productivity coefficient and aggregate index. By analyzing the results of the two methods, we turned the productivity prediction technology from single well to single sand layer, obtained successive evaluation parameters of reservoir productivity, and then optimized main layers and main contributed parts, which could guide the design of horizontal well trajectory.

A productivity model of vertically fractured well with varying conductivity for low permeability reservoirs

XIONG Jian，ZENG Shan，WANG Shaoping

2013, Vol.25(6): 122–126 Abstract ( 606 ) PDF (381 KB) ( 376 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.023

In view of that the flow conductivity of vertical fracture varies at different place after fracturing in the low permeability reservoirs, based on the change of fluid flowrule after fracturing, this paper established a productivitymodel of vertically fractured well with varying conductivity for lowpermeability reservoirs, considering the influence of starting pressure gradient, and analyzed the influences of different factors on productivity. The result shows that the influence of the attenuation coefficient on the oil well productivity increases with the enhancement of producing pressure drop, and decreases with the increase of crack length. When the fracture conductivity is small, the longer the crack length is, the bigger the attenuation coefficient is, and the less the oil well productivity is. On the contrary, the shorter the crack length is, the smaller the attenuation coefficient is, and the more the oil well productivity is.

Analysis and correlation of steady-state productivity formulas for horizontal wells

YUAN Lin，LI Xiaoping，ZHANG Lu，DU Lianlong，SUN Fei

2013, Vol.25(6): 127–132 Abstract ( 777 ) PDF (385 KB) ( 770 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.06.024

In the latest years, the studies on steady-state productivity theory for horizontal wells are more and more mature. Steady-state productivity formulas for horizontal wells in different methods emerge as the times require, but not all of the formulas can be used to predict the productivity of horizontal well accurately, so the logical choice of productivity formula is of great importance. Based on the pseudo-three-dimensional method, conformal mapping method and other related methods, this paper summarized the research progress of productivity theory for conventional horizontal wells all over the world, and made an applicability analysis of all the formulas by examples. The analysis result shows that if the reservoir type is the same with that shown in this paper, the formulas of Borisov （Lang Zhaoxin）, Giger, Renard-Dupuy (Guo Xiao and Li Zhenxiang), Fuirui and Chen Yuanqian are practical in predicting theproductivity in the field. The study can provide theoretical basis for choosing formula in reservoir devel opment reasonably.