Lithologic Reservoirs

As the rapid progress of computer techniques, the development of international geophysical exploration technologies could be summarized to three main trends. Firstly, the channel capacity of land equipments is 150 000 channels, the capacity of marine equipment is 26 cables, and in the future the equipments would develop to million channels. Secondly, acquisition technique would develop towards wide azimuth, high density, wideband vibroseis and dual-geophone cables techniques. Thirdly, processing technique would develop towards pre-stack depth migration, reverse time migration and full waveform inversion techniques. Since the Eleventh Five-year period, PetroChina always adheres to technical development. Keeping a foothold on four major fields, PetroChina continuously organizes geophysical exploration technical research, and obtained great development in the geophysical exploration technologies. However, compared with international major companies, PetroChina still fall far short of independent innovation abilities in equipment manufacturing, computer hardware capability and key geophysical exploration technologies. In view of current situation of international geophysical exploration technologies and based on the practical situation of each exploratory area of PetroChina, the application and future development of PetroChina geophysical exploration technologies are analyzed, and some advices are proposed.

Research on the flow mechanism of coalbed methane

LI Chuanliang，PENG Chaoyang

2011, Vol.23(4): 9–11 Abstract ( 569 ) PDF (306 KB) ( 522 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.002

Coalbed methane is an unconventional natural gas resource of self-generating and self-preserving. In order to develop the gas properly, it is necessary to study deeply the flowmechanismof coalbed methane. Coalbed methane is stored in the cheats of coalbed and pores of coal matrix, which is in the form of adsorption and coexists with formation water in coals. Coalbed methane must be desorbed from the pore wall before developed. Production of water from coalbed results in the drop of pressure, which leads to the desorption of coalbed methane to free gas. The coalbed methane desorbed flows to well bottomalong cheats in coals and then is developed to ground surface. The development of coalbed methane can be divided into three stages: degassing, desorption and flowing. Diffusion is not a part of flow mechanismof coalbed methane.

Evaluation methods for unconventional hydrocarbon resources

GUO Qiulin， ZHOU Changqian， CHEN Ningsheng， HU Junwen， XIE Hongbing

2011, Vol.23(4): 12–19 Abstract ( 543 ) PDF (795 KB) ( 788 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.003

The unconventional hydrocarbon resources are different fromthe conventional hydrocarbon resources in the aspects of accumulation mechanism, occurrence, distribution, exploration and development method, etc. As the strategic supplements of conventional resources, the unconventional hydrocarbon resources are becoming highly valued. But now, an effective evaluation systemis not yet built up for the evaluation of unconventional hydrocarbon resources in our country. Based on the accumulation mechanism and distribution characteristics of the unconventional hydrocarbon resources, five evaluation methods for unconventional hydrocarbon resources are introduced, including: analogy method, the major method of USGS; stochastic simulation method, the new developed method of USGS; reserve estimation method for single well, the typical statistical method; prediction method of hydrocarbon spatial distribution, the special statistical method; prediction method of continuous tight sandstone gas reservoirs, the special genetic method. These evaluation methods provide theoretical basis for the evaluation of the unconventional hydrocarbon resources and the newnational hydrocarbon resource.

Research progress in exploration technologies and environmental effects for gas hydrates

TANG Ruiling，SUN Zhongjun，ZHANG Fugui

2011, Vol.23(4): 20–24 Abstract ( 434 ) PDF (722 KB) ( 582 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.004

Gas hydrate is a kind of crystalicy substance formed by water and natural gas in special condition. Gas hydrate is a newtype of unconventional energy, which has wide prospecting potential. The exploration technologies and environmental effects of gas hydrates are summarized. The exploration technologies include seismic method, geochemical method, geophysical well logging method and other methods （direct drillingmethod, landform identification marks）. The environmental effects include submarine slump, greenhouse effect intensity, destroying marine ecological balance, etc. The research progress in the exploration and environmental effects for Gas hydrates is comprehensively reviewed.

Status quo of tight oil exploitation in the United States and its implication

LIN Senhu， ZOU Caineng， YUAN Xuanjun， YANG Zhi

2011, Vol.23(4): 25–32 Abstract ( 800 ) PDF (807 KB) ( 1260 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.005

The exploration and development of shale gas in the U. S. is progressing fast, which also leads to the development of tight oil. Tight oil is the oil accumulating within the shale system, including black shale with very low permeability, argillaceous siltstone and interbeded sandstone. Tight oil can be free oil or absorbed oil. It is a continuous reservoir of self-generation and self-storage. The development of tight oil in the U. S. mainly performed in Bakken, Eagle Ford, and the Barnett shale zone. Bakken shale has oil resource of 230×108 t and recoverable resource of 5.9×108 t. Bakken shale located within the U. S. has oil of 3.7×108 t and similar amount of associated gas. Its cumulative oil production since 2 000 is about 2.8×107 t. Eagle Ford shale produces oil in the northern part, annual oil production of about 2×105 t. Barnett shale has average undiscovered oil resource of 1.4×107 t, ofwhich undiscovered tight oil resource is 4.8×106 t. At present, Barnett shale has more than 8 000 producing wells, mainly produces oil in the northern part, gas in southern part. Up to the end of 2009, the cumulative oil production of “tight oil zone” has reached 7.7×106 t. China is a country rich in black shale. It is expected that the exploration of tight oil will get breakthrough soon.

Deep oil and gas accumulation conditions in Lengjia-Leijia area of Liaohe Basin

ZHOU Qi，LIU Xulong，NIE Shuang，JIAO Jianjun

2011, Vol.23(4): 31–34 Abstract ( 537 ) PDF (562 KB) ( 543 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.006

The degree of exploration in deep zones belowthe third member of Shahejie Formation in Lengjia-Leijia area is low. Based on the fine seismic structural interpretation and sedimentology study, the available data fromthe study area and adjacent areas are used to analyze the formation conditions of the deep reservoirs. The result shows that the NE main fault controls the regional structure and depositional patterns in Lengjia-Leijia area, which affects the oil and gas migration and accumulation, and the oil geological condition in the deep strata is favorable. There developed two sets of high quality source rocks in the third and fourth members of Shahejie Formation in Chenjia sub-depression, with an organic hydrocarbon generation intensity greater than 500×104 t/km2, which provides abundant oil sources for the surrounding areas. Favorable reservoir rocks exist in the forth member and lower third member of Shahejie Formation, Mesozoic and Archean, and good regional seals developed well in the middle section of the third member of Shahejie Formation. There are various traps, favorable oil and gas migration and accumulation conditions and great exploration potential. However, the factors affecting the reservoir formation are complex and there exist compound reservoirs. It is suggested that the next promising exploration targets should be primarily centered on the hill and lithologic reservoirs.

Control action of strike-slip faulting on hydrocarbon accumulation: A case study from Cenozioc fault in Qikou Sag

WANG Zhiyao， SU Junqing， QIAN Maolu， LIU Zhiying

2011, Vol.23(4): 35–40 Abstract ( 530 ) PDF (1072 KB) ( 527 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.007

Qikou Sag in DagangOilfield formed at the right lateral tensor shear background in Cenozoic, and developed two groups of fault（NNE-NE and NNW-EWtrending）, accompanying echelon brush structure fault. The changes of strikeslip displacement caused by strike-slip faultingmake the extension rift faulting coexist with the compression uplift and result in that the depocenter moved from outside to inside of the sag, and uplift and erosion outside of the sag occur simultaneously, which forms the model of “uplift in sag” that is easy to form self-generation and self-accumulation reservoir. The faulted slope break belts formed by strike-slip faulting constitutes the palaeostructure units and sedimentary facies boundary, and dominates the general depositional system distribution. Based on the concept of depositional system tract in sequence stratigraphy, the sedimentary facies controlled by strike-slip fault is analyzed under one system tract. The favorable source-reservoir-cap assemblages in actic region, gentle slope and sub-depression of Qikou Sag are discussed. The result shows that strike-slip fault controls the forming of lithologic-structural traps.

Characteristics of sedimentary facies and sequence stratigraphy of Changxing Formation in Fuling area, southeastern Sichuan Basin

GUO Chuan， LI Guorong， YANG Yingying， XIE Fachuan， DONG Wenyu， TANG Meng

2011, Vol.23(4): 41–47 Abstract ( 547 ) PDF (1187 KB) ( 648 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.008

Based on the knowledge of sedimentary and tectonic settings of Changxing stage in Fuling area in southeastern Sichuan Basin, under the guidance of the theory of classical sequence stratigraphy by Vail and high resolution sequence stratigraphy by Cross, by using outcrop, core and well logging analysis, the sequence boundary surface, facies sequence, stacking pattern and log curves are analyzed, and Changxing Formation in Fuling area is divided into two third-order sequences. The vertical and plane distribution of sedimentary facies of Changxing Formation in the sequence framework in Fuling area is studied, and the distribution of reef and shoal in Changxing stage is analyzed from the aspect of sequence evolution. The result shows that the reef and shoal bodies did not develop during the transgressive system tract phase in the third-order sequence of lower Changxing Formation in Fuling area, and then they developed fairly during the highstand system tract phase; reef and shoal bodies developed during the sedimentary stage of the third-order sequence of upper Changxing Formation, but their developing scales during transgressive system tract are signifi-cantly less than that during the highstand systemtract.

Reservoir characteristics of Archean magmatic rocks in Dongying Sag

GE Zhidan， WANG Xingzhi， ZHU Meng， PU Rui， WANG Wei， ZHANG Jinyou

2011, Vol.23(4): 48–32 Abstract ( 502 ) PDF (804 KB) ( 565 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.009

Based on core, rock slice, cast andmercury penetration data, the rock types, reservoir space types and reservoir properties of Archean magmatic rock reservoir in Dongying Sag are studied. It is considered that Archean magmatic rock reservoirs are mainly composed of brittle granide, dioritoid and dike rock, the reservoir spaces are mainly fractures, followed by dissolved pores and caverns, and the porosity and permeability both are low. So it belongs to pore-fractured reservoir with lowporosity and lowpermeability. The reservoir space ofmagmatic rock reservoir is mainly controlled by lithology, tectonic disruption and atmospheric fresh water leaching.

Reservoir characteristics and diagenetic facies of Chang 6₃ sub-member in Huaqing area, Ordos Basin

LIU Xiaoying， LI Tingyan， ZHANG Juzeng， YOU Yuan， MA Jiye

2011, Vol.23(4): 53–57 Abstract ( 464 ) PDF (759 KB) ( 800 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.010

The debris flowchannel deposits of sublacustrine fan of Chang 63 sub-member in Huaqing area, Ordos Basin are fromdifferent provenances, which could be divided into three parts, including the dominant northeast and southwest sources, and the minor mixed source. Based on the composition, diagenesis, and the differences and zones of plane diagenetic facies distribution ofChang 63 sandstone reservoir, it is determined that the provenances are the main factors that control the reservoir distribution. The chlorite cementation-intergranular pore diagenetic facies controlled by northeast provenance and the chlorite cementation-intergranular pore and feldspar dissolution diagenetic facies controlled by the western mixed source are the most favorable depositional-diagenetic facies zones. The research results can provide references for reservoir evaluation and development in Huaqing area.

Application of typical profile to analysis of reservoir pressure evolution and hydrocarbon accumulation in Dongying Sag

LI Jiting， ZENG Jianhui， WU Jiapeng

2011, Vol.23(4): 58–64 Abstract ( 507 ) PDF (1022 KB) ( 673 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.011

Basin modeling technology is applied to analyze distribution and evolution characteristics of abnormal pressure system of Cenozoic in Dongying Sag. Based on the analysis of hydrocarbon accumulation stages, the influence of reservoir pressure evolution on the hydrocarbon accumulation is studied. Numerical modeling result shows that abnormally high pressures occur in the third and fourth members （Es3 and Es4） of Eocene Shahejie Formation, and the pressures are mainly overpressure. The overpressure evolution in the sag is fluctuating and divided into three stages: original-forming, medium-declining adjustment and latest-raising stages, respectively corresponding to the stage of Shahejie to the final stage of Dongying Formation, the stage of uplifting and denudation, and the stage of Guantao Formation to Quaternary depositional stage. The study of overpressure evolution and hydrocarbon accumulation stages shows that the reservoir which is in the overpressure environment now may not be in overpressure environment when the hydrocarbon accumulation occurred. In the early time, the overpressure is favorable power for hydrocarbon migration and accumulation in the lithologic reservoir, and conducive to the preservation of lithologic reservoir.

Origin analysis of carbonate cements in Chang 8 reservoir in southeastern margin of Ordos Basin

ZHONG Jinyin， HE Miao， ZHOU Tao， HUANG Hao

2011, Vol.23(4): 65–69 Abstract ( 438 ) PDF (596 KB) ( 427 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.012

Carbonate cements are the most important authigenic minerals in Chang 8 reservoir in southeastern margin of Ordos Basin, and they are mainly ferrocalcite, with some dolomite and ferrodolomite. Based on thin slice and SEM inspection, inclusion enclave temperature measurement, carbon and oxygen isotope analysis and potassium ferricyanide coloring analysis, it is proved that calcite cementation started from the early diagenetic stage and lasted to the late diagenetic stage of B stage. In the early diagenetic stage, there generated light calcites, while to the late diagenetic stage, there generated a great quantity of ferrocalcites because of the organic material decarboxylation under thermocatalysis. Ferrocalcite generated in late diagenetic stage filled the remained intergranular pores with a semi-basal or basal cementation, which enormously lowers the accumulation capacity of the reservoir.

Heterogeneity of Chang 2 reservoir in Dingbian area, Ordos Basin

ZHAO Hesen， CHEN Yicai， TANG Bo， LIN Hangjie， LIU Yufeng， ZAHNG Yan

2011, Vol.23(4): 70–74 Abstract ( 396 ) PDF (674 KB) ( 534 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.012

Based on statistics of core and well log data, parameters of variation coefficient, dash coefficient and differential are calculated to carry out the study on the heterogeneity of layer, interlayer and areal heterogeneity of Chang 2 reservoir. The sand sets of Chang 2 reservoir are mainly of distributary channel sand bodiesin delta plain, and the layer heterogeneity is weak. There are many single sand bodies inside the reservoir, mud interbeds and barriers developed, and layer heterogeneity is relatively strong. In the plane, the reservoir heterogeneity in the distributary channel is weak and it is strong in the levee, crevasse splay and swamp. It is considered that Chang 2 reservoir in Dingbian area is of moderate heterogeneity.

Characteristics and controlling factors of E₁₊₂ clastic reservoir in Qie 6 block of Kunbei Oilfield in Qaidam Basin

LI Le，MU Zhonghai，WANG Liqun，XU Feng

2011, Vol.23(4): 75–80 Abstract ( 500 ) PDF (874 KB) ( 600 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.013

Based on the data of sections, cores, scanning electron microscope, mercury penetration and physical properties, the characteristics and controlling factors in Qie 6 block of Kunbei Oilfield in Qaidam Basin are systematically studied. The result shows that the clastic rocks are mainly arkose, lithic arkose and feldspathic litharenite with lowcompositional maturity and moderate-high textural maturity. The primary intergranular pores are the main reservoir spaces. The pore structure is characterized by high displacement pressure, small pore throat radius, poor connection and poor sorting. As low-porosity and low-permeability reservoir, it is mostly controlled by sedimentary microfacies and diagenesis such as compaction, cementation and dissolution, amongwhich compaction dominates when the depth increases to some extent.

Thrust and strike-slip deformation sequence of Micangshan structural belt

TANG Cong， LIU Shugen， LI Zhiwu， SUN Dong， SUN Wei， LI Jinxi

2011, Vol.23(4): 81–87 Abstract ( 429 ) PDF (1143 KB) ( 506 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.015

Micangshan structural belt is located in northern margin of Yangtze plate, which has transition relations with Longmen Mountain in west and south Daba Mountain in east. Under the multiple geodynamics of its peripheral orogenic belts, the study on structure and evolution of Micangshan structural belt is very important. Based on joint plane and scratch measured in Micangshan structural belt, Wulff net is applied to recover the palaeostress field. According to the intersection relation of joint fissures and the chronologic age of joint plane, combining with existing chronology data and fault features, the structure evolution ofMicangshan structural belt is reconstructed firstly. Micangshan structural belt experienced five phases of tectonic movement:①From200Ma to 160Ma, N-S thrusting compressional movement;②From 120 Ma to 100 Ma, S-Nstrike-slipping compressional movement;③95Ma, NW-SE compressional movement; ④From 50 Ma to 40 Ma, NE-SW compressional movement; ⑤15Ma, E-W compressional movement. In generally, the first and second phases of palaeostress field formed the Micangshan uplift and the E-Wstructures in the front area ofMicangshan, the third and fourth phases of palaeostress field superimposed the early structures and then formed superimposed structures in the front, and the fifth phase of palaeostress field finally make the Micangshan structure belt formed.

High resolution sequence stratigraphy of the eighth member of Yanchang Formation in Xiasiwan area, Ordos Basin

ZHOU Jingping， TANG Jun， ZHOU Xiaoyang

2011, Vol.23(4): 88–93 Abstract ( 433 ) PDF (1009 KB) ( 397 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.016

Under the guide of Cross high resolution sequence stratigraphy theory, based on areal geology, sedimentary facies, well logging, well drilling and core data in Xiasiwan area, the multistage cyclic sequence division scheme and electrofacies analysis technology are adopted to divide the eighth member of Yanchang Formation intomid-term, shortterm and super-short-term base level cyclic sequences. Every base level cyclic sequence can be subdivided into asymmetric upward-deepening, asymmetric upward-shallowing and symmetric base level cycles. The depositional setting，superposition style and sedimentary dynamics process of the super-short-term base level cyclic sequence are emphatically discussed. Isochronous stratigraphic framework of the eighth member of Yanchang Formation is established by making the short-term base level cycle as isochronous stratigraphic unit. This study provides geologic foundation for the cognition of sand body distribution lawand the planning of exploration and development scheme.

Study on sedimentary facies of Chang 8 member in Jiyuan Oilfield, Ordos Basin

ZHAO Xiaoqiang， WAN Youli， YI Chao， ZHANG Shimao， HE Yong

2011, Vol.23(4): 94–99 Abstract ( 596 ) PDF (850 KB) ( 891 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.017

Chang 8 member of Yanchang Formation is the major reservoir in Jiyuan Oilfield. With the development of oil and gas exploration, the areal heterogeneity of the reservoir has become an obstacle for further exploration and development, so the fine sedimentary facies description is particularly significant. Based on the analysis of sediment provenance and facies indicator, it is considered that Chang 8 member ofYanchang Formation is controlled by the provenances fromthe northwest and northeast, experienced the transformation from delta plain to delta front, and deposited distributary channel sand body which is superimposed vertically and continuous laterally. The physical properties of Chang 81 layer under different subfacies and different sources are contrasted. The result shows that the reservoir property of delta plain in Chang 81 layer is better than that of delta front, and the reservoir property controlled by the provenance fromnorthwest is better than that controlled by the provenance from the northeast. The favorable reservoirs of Chang 8 member are predicted, and it is considered that the reservoir in the northwest of Jiyuan Oilfield has great hydrocarbon potential.

Judgement of natural gas resource and accumulation analysis of the second member of Xujiahe Formation in Xiaoquan-Xinchang-Hexingchang area of West Sichuan depression

WANG Ruijing，LIU Shugen，ZHANG Guisheng，SUN Wei

2011, Vol.23(4): 100–105 Abstract ( 488 ) PDF (666 KB) ( 484 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.018

The analysis of natural gas composition and carbon isotope of the second member ofUpper Triassic Xujiahe Formation in Xiaoquan-Xinchang-Hexingchang area ofWest Sichuan depression indicates that the natural gas is hybrid origin consisting of coaliferous gas and oil-cracked gas. It has three sources:①source rock ofMaantang and Xiaotangzi Formation, humic-sapropelic organic material generated oil and gas and then the oil cracked into gas under high temperature;②source rock within the second member of Xujiahe Formation, gas-generated mainly, self-generating and self-reserving; ③source rock within the third member of Xujiahe Formation, which did few contributions to the gas accumulation of the second member of Xujiahe Formation. By analyzing the dynamic relationship between gas charging history and the rock-tightening evolution, the gas reservoir of the second member of Xujiahe Formation is judged as a typical “subsequent tight sand gas” reservoir, whose accumulation process conformed to the specific mode of “early accumulation-seal up-late activation”.

Application of forward modeling to research of carbonate cave response

LI Shengjun， LIU Weifang， GAO Jianhu

2011, Vol.23(4): 106–109 Abstract ( 528 ) PDF (485 KB) ( 411 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.019

The “string bead” reflection is one of the important seismic response features in identification ofOrdovician carbonation reservoir in TarimBasin. The mechanism of “string beads” is very complex. Base on forward modeling of wave equation, some different models are designed, and the influence of cave width and height on “string bead” characteristics is analyzed. The result shows that the amplitude of “string bead” intensifies with the cave width increasing, but the length of “string bead” do not change. The amplitude of “string bead” firstly intensifies and then decreases with the cave height increasing , and the“string bead” lengthens. Forward modeling provides approach for further study of response mechanismof cave, cave shape and “string bead” features, and criterion for semi-quantitative and quantitative forecast of carbonate reservoir.

Application of “two-step” facies-constrained stochastic modeling to reservoir description in Yanchang Oilfield

WANG Hong， WANG Beilei， WANG Chengjun

2011, Vol.23(4): 110–114 Abstract ( 426 ) PDF (737 KB) ( 533 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.020

The geological modeling for low permeability sandstone reservoir in Yanchang Oilfield is characterized by lack of data, poor accuracy degree and more uncertainty factors for reservoir description. Based on dense well logging interpretation, the “two-step” facies-constrained stochastic modeling method combining with core analysis and production performance are used to establish the facies model, and then carry out the porosity and the permeability modeling, in order to decrease the uncertainty for reservoir description. Taking BLC oil region in Yanchang Oilfield as an example, the “two-step” facies-constrained stochastic modeling method is applied to establish the low permeability sandstone reservoir model suitable for the actual production status in this area, which provides geological foundation for reasonable development decision and improving development effect.

Application of Kohonen neural network to 2D seismic facies division in E area of Qaidam Basin

LIU Xiaohong， FENG Mingyou， YANG Wuyang， SUN Hui， WEI Xinjian， LIU Zhe

2011, Vol.23(4): 115–118 Abstract ( 510 ) PDF (773 KB) ( 465 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.021

The situation ofE area is hard to proceed deep research and risk assessment by the absent of prospecting well data. Based on seismic mis-tie calibration, adjacent well calibration and fine horizon interpretation, Kohonen neural network method is applied to carry out two-dimensional seismic facies classification of target zone.Microfacies of delta front such as distributary channel, interdistributary bay and sand bar are recognized. The paleocurrent direction is suspected from southeast to northwest. Reservoir sand bodies developed well in the middle of the study area, preliminary prospecting well is located in favorable sedimentary facies. Sedimentary facies division are supplied and refined by the result of seismic facies，which can supply significant foundation for geometric arrangement of risk wells and regional breakthrough.

Study on effective method for development of heavy oil reservoir with high wax content in Jilin Oilfield

CHENG Jingbo

2011, Vol.23(4): 119–123 Abstract ( 455 ) PDF (506 KB) ( 667 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.022

Coil field is shallow heavy oil reservoir discovered recently in Jilin Oilfield. Due to the shallow burial depth, the reservoir temperature and pressure are low, the crude oil fluidity is poor, and the reservoir suffers easily wax precipitation code damage during the production process, which makes the low deliver ability, even no deliver ability.That seriously affects the normal production of oilfield and restricts the effective development of reserves in the area. In viewof this situation, crude oil wax precipitation experiment, physical simulation experiment and numerical simulation of thermal recovery are carried out. It is defined that the key for effective development is to increase the formation temperature, to maintain reservoir pressure and to prevent crude oil wax precipitation. Combined with the development effectiveness of the steam stimulation, steam flood and fire flood, it is defined that hot water drive can be used to most resources and fire flood can be used in local district with low temperature and high wax content.

Analysis of seepage-stress coupling field for lateral wells

WEI Chenxing， LIAN Zhanghua， DING Liangliang， GUO Yanruo， HAN Tao

2011, Vol.23(4): 124–128 Abstract ( 518 ) PDF (574 KB) ( 636 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.023

There is very strong fluid-solid coupling during seeping in porous media. Taking full account of fluid-solid coupling in the COMSOL software for multilateral wells, the distribution characteristics of coupling seepage and stress field are analyzed, and the dangerous section of sidewall is recognized according to calculating the value of fail coefficient by the Coulomb criterion. Through calculating the minimum value of fail coefficient and the volume integration in which fail coefficient is less than - 2.5 MPa, the impact of the build-up rate on sidewall failure is studied. The results showthat the changes of porosity is very small obtained in the simple seepage field by using unique compressibility factor, while the porosity and permeability of the coupling seepage field change remarkably in the vicinity of the bottom. Therefore, fluidsolid coupling seeping is a true reflection of underground seepage. In the stress field, both the maximum valve of Von Mises equivalent stress and the minimum valve of coefficients fail emerge in the side tracking point of the lower lateral, which means that the sidetrack windowis the dangerous section of sidewall. Finally, the conclusion of smallest range of rock failure drilling lower lateral with build-up rate of 15 /30m is obtained, which provides a the oretical basis for the designing and building of the multilateral wells.

Characteristics and genesis of super heavy oil reservoir with top water and edge water in Liaohe Oilfield

CAI Ye， FAN Zuochun

2011, Vol.23(4): 129–132 Abstract ( 443 ) PDF (418 KB) ( 718 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.04.024

Super heavy oil reservoir with top water and edge water in Liaohe Oilfield is characterized by gentle structure, coarse rock particles, good physical properties, weak diagenesis, poor heterogeneity, no oil-water interface. The genesis of this special reservoir is discussed. The result shows that biodegradation is material basis, hydrodynamic force and water washing make the buoyancy affect crude oil movement little, and the “asphalt shell” formed by oxidation prevents the formation water infiltration, which is favorable for reservoir preservation.