, Volume 34 Issue 2

    

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油气勘探
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  Petroleum enrichment rules in lithologic and stratigraphic pools in different faulted basins：An example from the correlation

  ZHAO Wenzhi and FANG Jie

  , 2007, 34(2): 1450-0.

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  Jizhong Depression in Bohai Bay Basin is a large-scale faulted basin developed in humid climate, while Erlian Basin is a small faulted basin group developed in semiarid climate. The pool-forming conditions and the rules of petroleum distribution and enrichment are different in them. Based on the correlation between the lithologic and stratigraphic pools found in Jizhong Depression and those in Erlian Basin, five rules of distribution and enrichment are summarized: the scale of basins decides the size of petroleum resources and pools; thickness of matured source rocks controls the pools longitudinal domains; the main oil-forming centers control the shapes of the pools planar distribution, e.g. lithologic pools along the main depressions in the Jizhong Depression are polycyclic-shaped along the depressions, while in Erlian Basin, the pools are hemicyclic-shaped inside the depressions; the geologic fabric builds the main direction of fluid potential and the pools distribution; plays in faulted basins control the pools enrichment.
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  Subtle buried hill reservoir accumulation conditions and exploration in Damintun Sag， Liaohe Oilfield

  LI Xiaoguang; GUO Yanmin; CAI Guogang; ZHAO Limin and WANG Guowen

  , 2007, 34(2): 1451-0.

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  Subtle buried hills (SBHs) of Damintun Sag refer to those low- or negative-shaped Protozoic or Archaean basement buried hills.The impervious Mesozoic Formation,Palaeogene Fangshenpao Formation or Es4 Formation seals the unconformity surface. Under multi-stage tectonic movement and weathering, the buried hills form favorable reservoir lithologies and fractured reservoirs. Inner buried hill laminar formation or lithology association together with minor faults form inner buried hill traps. Oil and gas from hydrocarbon kitchens migrate first along vertical deep fractures connecting source, laterally to SBH traps over a long distance along unconformity surfaces to form SBH reservoirs. The Protozoic SBH reservoirs have been discovered in the sag, including Anfutun, Ping'anpu and Dongshengpu. SBHs are deemed to be distributed extensively in depressions by their characteristics, and the space of exploration remains very vast.
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  Structure of unconformity and its control on hydrocarbon accumulation

  HE Dengfa

  , 2007, 34(2): 1452-0.

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  The structural characteristics of unconformities are analyzed with the Cretaceous base unconformity in Junggar Basin as an example. Unconformity surfaces are the carrier beds in most cases if sandstones develop on them. If weathering clay zones develop, the unconformities usually form traps. The unconformity surface, the fault, and the carrier bed constitute an efficient migration net. In faulted basins, hydrocarbons migrate and accumulate "near-source" in two ways, vertically migrating along the fault and adjusting along the unconformity in a steep slope, and horizontally migrating along the unconformity and vertically adjusting along the fault in a shallow slope. In depression basins, hydrocarbons accumulate "far from the source", pools are distributed step-like as a result of the step-like rising of the migration pathway net composed of faults and unconformity surfaces. Hydrocarbons accumulate "over the source" in fold-and-thrust belts of foreland basins, and the faults connect the above and below unconformities leading to the hydrocarbons being migrated in a zigzag style. The unconformity structures control the hydrocarbon migration and accumulation, and vary with time.
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  Macroscopic prediction of volcanic rock lithology: A case from Xujiaweizi Faulted Depression, northern Songliao Basin

  YANG Hui; SONG Jijie; WEN Baihong; XU Guangcheng and WANG Li-xian

  , 2007, 34(2): 1453-0.

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  Structure, fracture and lithology are the controlling factors for the accumulation and high productivity of oil and gas. According to the increasing density in the order of acidic, intermediate and basic volcanic rocks, a scheme of macroscopic lithological prediction of volcanic rocks is proposed by using gravity-seismic stripping enhancement. Based on a 3D density model constructed by seismic data, the stratigraphic gravity anomalies not relevant to volcanic formation are stripped off. The residual gravity anomaly is enhanced by narrow band-filtering to emphasize weak anomaly caused by deep-seated volcanic rocks and to remove regional background. By combining seismic, magnetic and drilling data, the macroscopic lithological distribution is predicted. The applicability of the scheme is demonstrated by a case from Xujiaweizi Faulted Depression, northern Songliao Basin.
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  Application of C7 light hydrocarbon parameters in identifying source rock depositional environment

  WANG Peirong; XU Guanjun; XIAO Tingrong and ZHANG Dajiang

  , 2007, 34(2): 1454-0.

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  The light hydrocarbon data of 170 oil samples of 11 Chinese oil provinces are selected from the KLPG database, of which 125 oils were analyzed by GC-MS. According to the geological background and the ratio of gammacerane/C31H(S+R), the oils stand for three depositional environments: saline lake, brackish to saline environment, fresh to brackish environment. Statistical analysis reveals that the group compositions of C7 light hydrocarbons are controlled by depositional environments. Oils of similar depositional environments have similar ratios of N/I (cycloalkane/isoalkane), I/P(isoalkane/normalalkane) and A/P(aromatic hydrocarbon/ normal-alkane). The oils in saline lakes are characterized by a high content of C7 aromatic hydrocarbon (30% on average) and a low N/I (below 2); those in brackish to saline environments have high C7 alkane (60% on average) and low N/I (below 2); those in fresh to brackish environments have high C7 cycloalkane (50% on average), high MCC6 (35%) and low N/I (below 2).
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  Evolution of the Jurassic sedimentary environment in northern margin of Qaidam Basin and its significance in petroleum geology

  YANG Ping; YANG Yuqin; MA Lixie; DONG Ning and YUAN Xiujun

  , 2007, 34(2): 1455-0.

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  The Lower Jurassic lithology at the Dameigou section of Qaidam Basin is characterized by fine-siltstone interbedded with carbargilite and shale. The carbargilite and shale of lake-swamp facies from the braided delta plain are more developed in Members One and Two of the Dameigou Formation, and most of them contain fossil conchostracans, bivalves and plants of a quiet-water environment. The sedimentary environment is a system of braided delta and shore-shallow lake, and three middle-period cycles constitute a long period fluctuation cycle of datum. Thick sandstones and conglomerates of fluvial-alluvial facies are more developed with fossil aspects mostly of ostracodes and plants in the Middle Jurassic, and the sedimentary environment is a system of fan-delta and shore-shallow lake with semideep lacustrine facies developed in the middle and upper parts, and a long period fluctuation cycle of datum is constituted by nine middle period ones. Fossils and sedimentary facies reveal the eastward transportation of the depocenter. Structural movement and climate influence the sedimentary environment greatly, and the former is a control factor. The braided delta plain under wet climate in Early Jurassic is the important hydrocarbon-generating site, but the semiarid climate in Middle Jurassic benefit a generation of high quality source rocks.
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  Hydrocarbon accumulating model and forecasting of favorable prospecting areas in buried hill of Budate Group, Beier Sag

  FU Guang and KANG Dejiang

  , 2007, 34(2): 1456-0.

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  The analysis of the hydrocarbon type, distribution and accumulating conditions in the buried hill of Budate Group in the Beier Sag reveals that the reservoirs formation and distribution are controlled by hydroncarbon-supplying window of K1n, source rock and caprock faulting, fracture-developing areas, collecting areas of oil-gas migration, and fault-bench and fault-horst hills formed in the middle-period deformation. There are two hydrocarbon accumulating models: accumulating in weathering crust in the top of the buried hill by migrating laterally through faults or unconformities, and accumulating in fractures or crushed zones in the buried hill by migrating vertically through faults. The most favorable prospecting areas are in the middle of the Sude'erte structural zone, around Well Bei 17 in the middle of the Huhenuoren fault nose structural zone, and around Well Bei 36 in the middle of the Aonaohai sub-sag. Other favorable areas are in the south of the Huoduomo'er anticline zone and around Well Bei 5 in the north of the Huhenuoren fault nose structural zone.
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  Aeolotropism and its exploitation significance of Chang 21 low permeability sandstone reservoir of Yanchang Formation, Shunning Oilfield

  WANG Jianmin

  , 2007, 34(2): 1457-0.

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  Synthetic analysis of the aeolotropism and oiliness of Chang 21 reservoir bed in Shunning Oilfield, Ordos Basin reveals: the reservoir has serious aeolotropism, developed compact interlayers, and permeability sections with the normal-abnormal rhythmicity; The aeolotropism is more serious vertically than horizontally, in river sides than in river body, and in Chang 212 reservoir bed than in Chang 211. Microsopic heterogeneity is the key factor restricting reservoir's permeability. Sedimentary facies belt and diagenesis obviously control the permeability, which influences the oil-gas distribution and water injection profile or production profile. The compact interlayers in Chang 21 can effectively block vertical seepage of liquids, restrict intralayer seepage, and stop artificial cracks from breaking through. They are favorable to collecting water drive energy, increasing water drive efficiency and reserves utilization degree, and are the important basis for dividing exploitation members and working out water-injection development plan.
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  3D modeling of Ordovician fractured-vug carbonate reservoir, Tahe Oilfield

  ZHANG Shupin; CHEN Fuli and JIN Yong

  , 2007, 34(2): 1458-0.

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  Fractured-vug carbonate reservoir is the main reservoir of Ordovician carbonate reservoirs of Tahe Oilfield; this highly heterogeneous reservoir has gone through a long geological time and complex structural movements. In order to design a comprehensive scheme of stabilizing production and controlling water for the pilot area, 3D geological models are established by using variance from seismic, karst facies control modeling, cloud transform technology etc. to combine geological, geophysical, reservoir engineering data. The distribution of the reservoir is predicted by structural modeling, karst modeling, property modeling, fracture analysis, and model analysis. A more geologically reasonable model for the reservoir simulation is got using this adjusted modeling. The favorable reservoir is in conformity with the upper part of the structure in the area, and the reservoir development and the structural deformation degree relate to karstification. Both porosity and permeability are low and their distribution is random.
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  Cretaceous Fuxin Formation coalbed methane system in Fuxin Basin

  ZHU Zhimin; SHEN Bing; LU Aiping and YAN Jianfei

  , 2007, 34(2): 1459-0.

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  The Fuxin Formation coalbed methane system is studied using the theory and method of non-conventional petroleum system. The source and reservoirs are Sunjiawan, Zhongjian and Taiping coal seams of the Fuxin Formation. The coalbed methane is sealed by the roof comprised by mudstone, siltstone, and bauxite of the upper Fuxin Formation. The overburden is the upper Fuxin Formation and the Sunjiawan Formation deposits. The hydrocarbon generation of the source rocks reaches its first peak in the late Sunjiawan period, and the highest maturity is about Ro =0.67%. The dolerite intrusion during the Himalayan orogeny enhances the coal maturity and causes a second peak of hydrocarbon generation with the highest maturity up to 4.95% at local areas. The underwater brings many bacteria generating second biogenic methane. Then the coalbed methane is reserved and the critical moment of the coalbed methane system is at the end of the Late Paleogene Period. The Fuxin Formation coal seams are favorable for coalbed methane exploration.
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  Sandstone distribution pattern and the exploration of lithologic reservoirs in the Es3 member of Xinglongtai area, Liaohe Depression

  GAO Xianzhi; LI Xiaoguang; LI Jingsheng; SHAN Junfeng; XIE Yubao and LIU Baohong

  , 2007, 34(2): 1460-0.

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  The Xinglongtai area is located in the Western Sag of Liaohe Depression. In the Early Tertiary, the Western Sag was strongly extended, and turbidity deposit prevailed in the sag. Meanwhile, an underwater highland in the area blocked sand and gravel turbidity current from the eastern sources, and the turbidity was compelled to pour and deposit into the eastern slope of the highland and in the deep sag, forming up dip pinchout and lenticular sandstones. The sandstones occur vertically along sequence interfaces near the bottom of the transgressive system tract and the upper of the regressive system tract, and also along the maximal flooding surface. The distribution pattern of the sandstone (turbidity sandstone) along the sequence interfaces illustrates that faulting is the key-controlling factor on the changes of the water level and turbidity deposit. This distribution pattern of the turbidity sandstones is helpful to predict the distribution of lithologic reservoirs.
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  Exploration potential contrast of non-sandstone reservoirs within salt-layers between Shashi and Qianjiang Formations, Jianghan Basin

  CHEN Bo; XIAO Qiugou; CAO Weisheng and ZHAO Haitao

  , 2007, 34(2): 1461-0.

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  Non-sandstone reservoirs within salt-layers of self-generation and self-storage exist in Qianjiang Formation. Salt also deposit in the Shashi Formation of Jiangling Sag, but non-sandstone reservoirs poorly developed. The different characteristics of the two formations and their rhythms are controlled by tectonic environments and paleoclimates. In the Qianjiang Formation, the strong faulting causes a deep-water compensation or insufficient-compensation depositional environment favorable for organic matter to deposit. The saline rhythm consists of pure salt rock and non-sandstones within salt rock, such as dark-grey mudstone, oil shale, glauber-bearing dolomite and dolomite. Because of the source rocks of mudstone, the reservoir of oil shale and dolomites, the non-sandstone reservoir has a great exploration potential. In Shashi Formation, the faulting is weak and the climate dry, leading to a compensation or overcompensation depositional environment unfit for organic matter to deposit. The saline rhythm consists of gypsum-bearing salt rock and purple or gray mudstone or glauber-bearing mudstone. Poor source rock and reservoir indicates a poorer exploration potential than that in the Qianjiang Formation.
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  Fault sealing performance in Chenbao and eastern Chenbao areas, Gaoyou Sag

  QIU Yibo; ZHA Ming and QU Jiangxiu

  , 2007, 34(2): 1462-0.

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  In complex fault-block regions, it is important to study fault sealing performance to determine the distribution of reservoirs. By several factors that can influence sealing performance, such as the lithologic association on two sides of fault, the mudstone-smearing analysis, the relationship between fault-moving periods and hydrocarbon migration periods, and the mechanical properties of fault, this paper studies the fault sealing performance in Chenbao and eastern Chenbao areas. Fault sealing performance is evaluated using the fuzzy synthesized evaluation method. The results show that fault sealing is worse during the Sanduo stage, in which fault became oil and gas migration pathways. From late Sanduo stage to now, fault sealing is better, which is beneficial to reservoir conservation.
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  Application of pre-stack elastic parameter inversion in Huangjue Oilfield

  LIANG Bing; YANG Jianli; ZHANG Chunfeng; CHANG Xinwei and XIE Deming

  , 2007, 34(2): 1463-0.

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  The prediction of lithology using elastic parameters is presented for the exploration of lithologic oil reservoirs in the Huangjue area. Two elastic parameters (bulk modulus (K) and EI(30)) are more sensitive to sandstone and claystone based on the sensitivity analysis of eight elastic parameters. Three elastic parameters (P wave velocity, bulk modulus (K) and EI(30)) were inverted using pre-stack time migration CRP gather data and well log data through pre-stack elastic parameter inversion. It is obvious that bulk modulus (K) and EI(30) are better than P-wave velocity for sand discrimination. Two fans (Ed24) develop in the study area, one is located at the west of Wells H83 and H32, NS trending; the other is located at the area between Well H83 and Well H11, NE trending. Number 2 sandbody of the six sandbodies is the most favorable exploration target in the area.
油气田开发
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  The middle Shahejie Formation of Block Hu 12, Dongpu Sag belongs to fan-delta deposition. High capacity channels are formed in the 4th 8th sand units due to long time water-flooding developments. They are mainly distributed in the sand beds of subaqeous

  ZHONG Dakang; ZHU Xiaomin; WU Shenghe; JIN Song; JIA Daji and ZHAO Yan

  , 2007, 34(2): 1464-0.

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  The middle Shahejie Formation of Block Hu 12, Dongpu Sag belongs to fan-delta deposition. High capacity channels are formed in the 4th 8th sand units due to long time water-flooding developments. They are mainly distributed in the sand beds of subaqeous channel and mouth bar micro-facies whose thicknesses are more than 3 meters, on the lower part of normal grain rhythm of subaqeous channel sandstones and on the top part of reverse grain rhythm of mouth bar sandstones, whose porosity and permeability are over 20% and 100mD respectively. Their formation is attributed to high maturity, low diagenesis evolution, and long-term water-flooding. The porosity of sandstones increases by 3%~5% and permeability by 5-20 times, the width of pore throats is enlarged. The base line of spontaneous potential is uplifted, the differences of microelectrode and acoustic travel time increased, resistivity decreased. The water absorption is higher than that in the adjacent beds. As water injection increases, liquid production increases, but oil production and injection pressure decrease.
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  A laboratory study of enhancing oil recovery with petroleum sulfonant system after polymer flooding

  ZHU Yangwen

  , 2007, 34(2): 1465-0.

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  A laboratory study of further enhancing oil recovery (EOR) with a surfactant, mainly consisted of petroleum sulfonate, was done, after polymer flooding, for the Ng4 sandstone formation of No.1 Block of Central Gudao Oilfield in Shengli Oilfield complex. A compounded system mainly composed of petroleum sulfonate was developed and then an oil displacement efficiency experiment was carried out. By comparing results of several oil displacing systems of surfactants with low interfacial tension, the optimum petroleum sulfonate oil-displacing system, 0.3% SLPS-01C+0.1% co-agent 1#, was screened out. The influence of converting time of injection on the EOR of petroleum sulfonate system was studied as well. The best oil-sweeping and oil-displacing results can be obtained when the petroleum sulfonate system begins to be injected at the lowest water-cut after the polymer flooding, the reason is that, owing to the polymer flooding, an “oil bank” is formed, preventing the channeling of the surfactant.
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  Phased flow unit model establishment and remaining oil prediction: An example from Jing 11 block in Bieguzhuang Oilfield

  PENG Shimi; ZHOU Hengtao; LI Haiyan; ZHANG Wensheng and HU Haitao

  , 2007, 34(2): 1466-0.

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  The Jing 11 block in Bieguzhuang Oilfield has entered the high water-cut period, the production decline is quick and the reservoir heterogeneity is serious.Based on the core data analysis, the reservoir is divided into four kinds of flow units using the cluster and discriminatory methods and the optimized macroscopic and microscopic parameters related to reservoir lithology, physical property and interstitial flow. Flow unit models are therefore established corresponding to different development periods (initial, intermediate and late) according to the water saturation characteristics, and the change of the flow units is studied. The distribution of the remaining oil in the block is then predicted with the remaining oil calculation in the development tail. The study indicates that in different development periods, the distribution has a close relationship with flow unit types, and in the late period of development, the flow units of types 3 and 4 are the richer accumulation areas of remaining oil.
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  Experimental study of water-rock reaction during thermal production

  GUO Ping

  , 2007, 34(2): 1467-0.

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  The speed and degree of water-rock reaction will increase with temperature, and mineral fines produced by chemical reaction contribute mainly to pore block when temperatures reach 200～300℃. Take petroliferous fine siltite (S1) and oil-rich siltite (S2) of Gudao field as experimental samples, this paper has studied the water-rock reaction mechanism at different temperatures and initial pH values of injected fluid. The experiment indicates that the dissolution and precipitation of minerals is the main factor to cause reservoir damage. At high temperatures, the primary minerals in sand reservoir, such as quartz, potassic feldspar, sodium-calcium feldspar,dissolve and new minerals produce. The precipitated minerals beome the main source to pore block. The experiments of different initial pH values show that when pH value is 9, the solution of minerals is most for clay-rich rock, and the solution of minerals is least for clay-poor rock.
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  Calculating method of shut-in time for pressure survey in production wells in low permeability oil reservoirs and its application

  TIAN Leng; HE Shunli; LI Xiusheng and GU Daihong

  , 2007, 34(2): 1468-0.

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  The reasonable time limit of shut-in wells and its computational method for fractured wells in low permeability reservoirs were studied by the modern well test interpretation in Chang 2 low permeability oil pool of Sai 39 block in Suijing of Changqing Oilfield. The results show that when the time of shut-in pressure survey triples the occurrence time of radial flow, the error of well-testing results about the formation parameters and formation pressure gained by pressure data at this moment is smaller than 5%. The border types can be diagnosed. The theoretical curve is similar to the Horner method interpretation value. For Sai 39 block, if effective permeability is given, shut-in time for pressure survey can be obtained by the theoretical curve. Otherwise, according to the effective permeability in this block (about 6mD), it is proposed that the measuring time of transient well testing be controlled for more than 25 days.
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  A kind of flexible water shutoff agent applicable to reservoirs with high temperature and salinity

  ZHU Huaijiang; WANG Pingmei; Liu Qiang; XIONG Chunming; LIU Yuzhang; LUO Jianhui and YANG Jingbo

  , 2007, 34(2): 1469-0.

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  Swellable gel particles of pre-crosslinking polymer/fiber and polyacrylamide gel cannot be used as water shutoff agents in the reservoir of high temperature (>120℃) and salinity for their bad thermal stability in brines of high salinity. A flexible water shutoff agent (SR-D1) applicable to those reservoirs is developed. The agent is particles with a size range from 1 mm to 8mm, and does not dissolve in water, but is slightly soluble in oil, and with a high elastic deformation capability. Its chemical stability is high under the high temperature and salinity conditions, and it could form integrated plugged zones by means of secondary bond. Under the reservoir condition of Tahe Oilfield, the plugging efficiency increases drastically with the SR-D1 volume increasing from 0.03PV to 0.2PV, and the fractures and high permeability channels are sealed strongly in the reservoir. It is easy to be broken down with methylbenzene if misplugging happens.
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  SAGD process with the combination of vertical and horizontal wells in super-heavy oil reservoir

  LIU Shangqi; WANG Xiaochun; GAO Yongrong; YANG Liqiang and YOU Shi-jiang

  , 2007, 34(2): 1470-0.

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  Xinglongtai Formation in Block Du 84 of the Shu-1 heavy oil area, Liaohe Oilfield, is a massive-block extra-heavy oil reservoir, with the oil viscosity greater than 100Pa·s at 50℃. This paper presents the feasibility of SAGD process with the combination of vertical and horizontal wells based on the reservoir characteristics, oil properties and development status. Well patterns are investigated using numerical simulation, and the parameters of injection and production are optimized after several cycles of steam stimulation with the formation pressure greatly reduced. The SAGD process is viable and the recovery factor is increased by 30.0% with the cumulative oil steam ratio of 0.296. The optimum well pattern is that horizontal wells with 20m apart are drilled between and beneath two rows of vertical wells. The horizontal well length is 280m. The steam quality at down-holes must be greater than 70% and the drawdown capacity in production wells have to be matched with the injection rate in injection wells.
石油工程
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  Current status and prospect of key techniques for exploration and production of tight sandstone gas reservoirs in China

  KANG Yili and LUO Pingya

  , 2007, 34(2): 1471-0.

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  Tight sandstone gas (TSG) reservoirs in China display such characteristics as low porosity and permeability, naturally fractured, partially ultra-low water saturation, high capillary pressure, abnormal formation pressure and high damage potential. Over 10 years, a set of protection technology of temporary shielding, gas drilling, and under balanced completion during entire well operation have been formed for fractured TSG reservoirs. The fracturing fluids include CO2 foam, N2 energized water-based fluid, and guar organoborated gelling fluid with low frictional resistance and high viscosity. Massive hydraulic fracturing by high injection rate through casing has been applied in fields. Employing both damage control and stimulation and realizing protection technology are the important guarantee for pay zone detection, precise evaluation and economic development. It is proposed to strengthen fundamental research on petrophysics of tight sandstones, improve reservoir protection matching technology during drilling and completion, propagate horizontal wells and complex wells, enhance applicability of fracturing stimulation, and establish integrated technologies for different types of TSG reservoirs.
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  Review of deepwater dual gradient drilling technology

  CHEN Guoming; YIN Zhiming; XU Liangbin and JIANG Shiquan

  , 2007, 34(2): 1472-0.

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  To overcome problems associated with deepwater drilling, a new technology known as "dual gradient drilling (DGD)" has been introduced. Several new approaches to the deepwater dual gradient drilling were developed, including subsea mudlift drilling, riserless drilling, and dual density drilling. The research and application of some joint industry projects were reviewed, such as Conoco/Hydril subsea mudlift drilling system, Shell subsea pumping system, Baker/Transocean DeepVision pump system, MTI hollow sphere dual gradient drilling system, AGR Subsea riserless mud recovery system, as well as LSU riser gaslift and riser dilution, etc. Compared to conventional drilling techniques for deepwater drilling, the dual gradient drilling technology has the following advantages: lower cost, shorter well construction time, more operation safety, and increased production. It has a large potential market in the future exploitation of deepwater oil and gas in China.
国际交流与合作
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  Hydrocarbon accumulation conditions and geologic risks of Kufra Basin, North Africa

  CHEN Zhongmin; PAN Xiaohua; HUANG Xianxiong; ZHANG Jinhai and ZHOU Li-cheng

  , 2007, 34(2): 1473-0.

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  Kufra Basin is a large Palaeozoic intracratonic sag basin, which is formed on the crystallization basement. The hydrocarbon geologic evaluation reveals that the basin fill consists of shallow marine to continental fluvial deposits ranging in age from Infracambrian to Cretaceous. Eight sections of reservoir are classified based on drilling data, outcrops and palynologyic association. Three sets of source rocks are predicted to exist in the basin, namely, Infracambrian black shale or limestone, Ordovician shale and Lower Silurian shale (Tanezzuft Formation). The Lower Silurian shale is the most possible source rock. Two potential plays of Ordovician-Silurian and Infracambrian are predicted to exist in the basin. Basin modeling shows that the potential source rocks of the two depo-centers (Uri and Kalanshiyu Troughs) reached the oil-generating window. Whether effective source rocks exist or not is the main element of determining the hydrocarbon potential and the riskiest geologic element for hydrocarbon exploration.