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01 October 2011, Volume 32 Issue 5 Previous Issue    Next Issue

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New Understanding of Delta Depositional Model JIN Zhen-kui, HE Miao 2011, 32 (5):  443-446.  Abstract ( 170 )   PDF (412KB) ( 579 )   Save Through flume experiment and investigation of modern deltas, it is found that in front delta, underwater distributary channels are not formed, the distributary channels of delta plain disappear immediately once extending to the lake (sea) level; front delta sand bodies are usually sheet-shaped and fan-shaped, instead of ribbon shaped. These are different with the traditional understandings of them. The study suggests that depositional model of fan deltas differs widely from that of river deltas. On alluvial fans and fan delta plain develop two types of topography units: channel and inter-channel, both of which are sandy-conglomeratic deposits. There is not environment for shale or mudstone deposition. The mudstone deposit interbeded with sand-conglomerate is actually formed at pre-fan and inter-fan during regression of alluvial fan or when the alluvial fan is abandoned. The deposits of front fan deltas are dominated by sandyconglomeratic deposit from channel flow and sheet flow. Sand- conglomerates from channel flow form mouth bars, and those from sheet flow form underwater sheet flow shoal, both of which are connected together to shape sheet-like sandy-conglomeratic deposits, and further connected with those of fan delta plain. References | Related Articles | Metrics

Wuerhe-Xiazijie Strike-Slip Structure and Petroleum Exploration Significance in Northwestern Margin of Junggar Basin ZHANG Yue-qian, WANG Xin, LIU Ji-shan, LIANG Han, LI Zhen-hua, WANG Ren-fu 2011, 32 (5):  447-450.  Abstract ( 138 )   PDF (541KB) ( 439 )   Save New structural studies and 2-D and 3-D seismic profiles reveal that in the Upper Paleozoic-Mesozoic in western Junggar basin develop Dalabute strike-slip fault and Karamay-Xiazijie fault belt. The former assumes normal flower-shaped structures, the latter develops right strike-slip structures which form en echelon arrangement of Wuerhe antiline, Xiazijie anticline, high angle-dipping shear faults. In Late Paleozoic-Mesozoic the northwestern margin of Junggar basin occurred strike-slip movement dominated by right shear and overthrust structures, shaping the strike-slip faults and shear fault dogleg folds. This could deny the previous long-time idea of that in the northwestern margin of Junggar basin developed overthrust nappe structure. It is the collision between Cenozoic India plate and Eurasia that caused the reactivation of Dalabute fault along left strike-slip, while Karamay-Xiazijie fault belt was not activated in Cenozoic. References | Related Articles | Metrics

Fluid Inclusions and Gas Accumulation of Permian in Eastern Ordos Basin LI Yan-xia, ZHAO Jing-zhou, LI Jing-hong 2011, 32 (5):  451-456.  Abstract ( 86 )   PDF (1231KB) ( 271 )   Save The gas accumulation time and process of the Permian (including Taiyuan, Shanxi, Shihezi and Shiqianfeng formations) gas reservoirs in eastern Ordos basin were described by reservoir fluid inclusions. The result shows that the Upper Paleozoic reservoirs are rich in type of fluid inclusions, mainly including saltwater inclusion, hydrocarbon-bearing inclusion and gaseous hydrocarbon inclusion. The distributions of homogenization temperature of the fluid inclusions in different gas strata are of significant differences with single frequency, dual-frequency or multi-frequency. The reservoir fluid was characterized by high salinity. Integrated with the burial history and thermal history analyses, the effective gas accumulation times of Taiyuan, Shanxi, Lower Shihezi and Upper Shihezi-Shiqianfeng gas strata were determined. The gas accumulation process of the Permian gas reservoir groups could be divided into two stages: the early durative stage from Jurassic to Early Cretaceous, in which the primary gas reservoirs of Taiyuan and Shanxi formations were formed with "diffused gas pool" in Lower Shihezi Formation; the late lifting and adjustment stage of Late Cretaceous, in which natural gas was quickly adjusted by way of bunched flow, with connections among micro-fractures and faults, and Lower Shihezi gas reservoir and Upper Shihezi- Shiqianfeng secondary gas pool were formed. References | Related Articles | Metrics

Characteristics of Volcanic Reservoir Fractures in Upper Wall of HongChe Fault Belt SU Pei-dong, QIN Qi-rong, YUAN Yun-feng, JIANG Fu-dong 2011, 32 (5):  457-460.  Abstract ( 113 )   PDF (514KB) ( 293 )   Save The fractural types in Hongshanzui-Chepaizi (HongChe) fault belt in Junggar basin mainly include 4 non-structural fractures (interlayer fracture, stylolite, dissolution fissure and diagenetic fissure) and 4 structural fractures (horizontal fracture, low-angle fracture, diagonal seam and high-angle fracture), according to the study of core fracture and well logging data. The statistics show that about 50% of HongChe fault fractures are totally filled, 37% semi-filled, 13% unfilled. The types of filled minerals are calcite, anhydrite, zeolite, silica, chlorite, and other authigenic ones. The fissure width ranges from 0.1 mm to 20 mm, dominated by 1~4 mm; the fractural dip ranges from 10° to 50°, which account for more than 90% of statistical fractures. The trend of the fractures is dominated by NE , the secondary is near SN and NW. Favorable structural positions where fractures developed are mainly on structural highs, structural intersection and fault-developed area. The fracture developing extent is increasing with the increase of fragility of reservoir rocks. The fracture development and opening are all decreasing with the increase of reservoir burial depth. References | Related Articles | Metrics

Forming Conditions of Effective Reservoir of Nantun Formation in Wunan Sub-Sag of Hailaer Basin BAO Yuan, LUO Qun, WEI Chong-tao, WANG Chao-yong, ZOU Ming-jun 2011, 32 (5):  461-463.  Abstract ( 78 )   PDF (193KB) ( 213 )   Save The results from laboratory study and comprehensive analysis show that the effective reservoir of Nantun formation in Wunan sub-sag of Hailaer basin is dominated by normal terrigenous clastic reservoir with some tuff sedimentary rocks. The developed sections and secondary porosity developed sections in this reservoir are of good corresponding relations. The development of secondary porosity is affected by many factors, for example, the weathering leaching on unconformity and organic acid dissolution are main control factors for the secondary porosity; the particle propping effect of high structural maturity is major control factors for the primary porosity; weak compaction and authigenic clay mineral shell are also favorable effects on the formation of effective reservoir, and the sedimentary facies of delta front controls the distribution of the Nantun effective reservoir. References | Related Articles | Metrics

Alkali Diagenesis of Xujiahe Sandstone in Hebaochang Block in Sichuan Basin ZHANG Sheng-bin, LIU Zhen, LIU Hong-jun, SONG Ya-hui, LI Xin-min, XU Tao 2011, 32 (5):  464-468.  Abstract ( 87 )   PDF (868KB) ( 296 )   Save The typical quartz dissolution of alkali diagenesis of Xujiahe formation in Hebaochang block in Sichuan basin is firstly discovered, which forms secondary porosity characterized by such a quartz dissolution. Based on the analyses of thin section, scanning electron microscope, X-ray diffraction, combined with the regional geology conditions, the characteristics and formation mechanism of alkali diagenesis in this area are studied. The results show that the sandstone of Xujiahe formation undergoes strong diagenesis and enters into the stage of late diagenetic B, with transition from early acidity to late alkalinity. The alkali diagenesis reconstructs the sandstone of Xujiahe formation and allows its physical property to be much better. References | Related Articles | Metrics

Analysis of Dynamic Connectivity on Carbonate Reservoir with Fracture and Cave in Tahe Field, Tarim Basin YI Bin, CUI Wen-bin, LU Xin-bian, YANG Min 2011, 32 (5):  469-472.  Abstract ( 129 )   PDF (336KB) ( 347 )   Save The Ordovician reservoir in Tahe field is a large carbonate reservoir with fractures and caves. The reservoir pore spaces are various caves, fractures, solution pores and micro-fractures. The reservoir development practice confirmed that this reservoir is characterized by multi-fractures-caves, multi-pressure systems and multi-flow units. This paper proposes the analytical methods for using dynamic information to analyze connectivity between fracture and cave, including the reservoir pressure trend analysis, the interwell production interference analysis, the fluid property difference analysis, the interwell interference well test analysis and tracer testing analysis, etc. Also, combined with Tahe actual production data, the flow units are classified and analyzed preliminarily. References | Related Articles | Metrics

Resource and Exploration Prospect of Oil Shale in Kazuo Basin GUO Qiang, WANG Yu-lin, ZHONG Da-kang, LI Xi-hai 2011, 32 (5):  473-475.  Abstract ( 153 )   PDF (211KB) ( 293 )   Save Based on the field geological survey and the previous research achievements, oil shale characteristics in Kazuo basin are presented, the resources type and distribution are found out, the exploration targets selection is optimized, and then the exploration deployment suggestions are put forward. In Member No.1, No.2 and No.3 of Jiufotang formation in this basin developed first, second and third oil shale groups respectively, among which Group 3-1 oil shale appears in many outcrops, with big thickness and high control degree. The type of oil shale is mainly grey-black, brown-black mudstone, most belong to medium-low grade refractory high ash oil shale. The type of resource is predicted resource and the data show that Group 3-1 is of the greatest industrial or commercial significance, which mainly occurs in Meileyingzi sag. Based on the results of selection of oil shale exploration targets, it is suggested that Kazuo basin can be divided into all-round systematic exploration area, extensive network exploration engineering operation area and special geological survey area in terms of exploration deployment. References | Related Articles | Metrics

High-Resolution Sequence Stratigraphy Division and Its Paleoecology Response from Drilling Records—An example from Xiayoushashan formation in Wunan area of Qaidam basin YANG Ping, ZHANG Dao-wei, YUAN Xiu-jun, ZHANG Ying, WU Ming-sheng, YAN Xue-gang, ZHANG Hai-yang 2011, 32 (5):  476-479.  Abstract ( 117 )   PDF (467KB) ( 286 )   Save In the chronostratigraphy framework, utilizing the high resolution sequences base-level cycle to identify sequences boundaries, the Xiayoushashan formation of Nancan-2 well in Wunan area of Qaidam basin can be divided into two medium base-level cycles (Class-3 sequence). The changes in sedimentary environment and base-level cycles is interactional, so the sedimentary facies and paleoecology characters are significant evidences on the cycle division. The well sedimentary facies can be divided by references to sedimentary characters of fluvial and lacustrine sands and mudstone at Xiayoushashan formation of Xichagou outcrop, the paleoecology types include shallow water, deep water, fresh water and brackish water. Therefore, the isochronous stratigraphic framework of Wunan area is established, the relations between base-level cycles and paleontology responses are then analyzed. References | Related Articles | Metrics

Diagenesis of Volcanic Rocks and Its Effects on Physical Properties of Reservoirs of Kalagang Formation in Malang Sag of Santanghu Basin LEI Hai-yan, LIU Cheng-zhi, HE Ren-zhong, WANG Xin, CHEN Xuan, YU Hai-shan 2011, 32 (5):  480-483.  Abstract ( 106 )   PDF (964KB) ( 319 )   Save Based on the core description, thin section analysis, pore character, microphotograph and scanning electric microscope observation, the petrological characteristics and diagenesis of volcanic reservoirs of Kalagang formation of the Upper Carboniferous in Malang sag are studied. The results show that the volcanic rocks of Kalagang formation consist mainly of basalt, andesite and volcanic breccia; the vaporization of volatile matter, dissolution, weathering and leaching process allow the reservoir quality to be better, the filling process makes the reservoir quality become poor, and the metasomatism is of the dual nature. The horizon of Metasomatism and the level of filling after mineral transmigration have a regularity of vertical zonation, of which the former becomes better in petrophysical property. References | Related Articles | Metrics

Research on Fine 3-D Geology Modeling LI Jun-jun, WANG Zhi-zhang, ZHANG Zhi-huan, JIANG Dan, WANG Li-chang, ZHANG Xiao-feng 2011, 32 (5):  484-486.  Abstract ( 126 )   PDF (923KB) ( 613 )   Save In the present conditions of computer resources, the digitization of every link of fine reservoir description has been realized. Application of high-precision 3-D geology modeling greatly improves the speed and accuracy of oil-gas reservoir research. 3-D reservoir model provides supports for reservoir numerical simulation and for reservoir evaluation and design of development plan. In Karamay Fengcheng oilfield, the reservoir modeling in some new prospecting districts often appear in such a situation as large area and less well like bull's eye due to a few wells. In order to improve the simulation precision in this oilfield, the adjacent dense well patterns in the old districts are applied to determine variogram which is then used for modeling of sparse well-pattern area, and good effect of modeling has been achieved. References | Related Articles | Metrics

Reservoir Stress and Fracture Distributions of Su-10 Block in Ordos Basin GUO Peng, LI Chun-lin, HA Wen-lei 2011, 32 (5):  487-488.  Abstract ( 91 )   PDF (201KB) ( 403 )   Save This paper analyzes the regional tectonic stress field characteristics in Ordos basin, develops the reasonable geological and mechanical model of its Su-10 block based on the finite element basic theory, and presents the maximum horizontal principal stress, minimum horizontal principal stress, maximum shear stress, mean stress and deformation energy contour distribution diagram of the target zone by numerical simulation of the earth stress field. The evaluation indices such as "3-D equivalent tensile stress (σT)", "crack value (I)" and " strain energy per volume (u)" are applied to get composite assessment factor (Rc) for quantitative description of the fracture development. It is indicated that the zones with developed structural fractures are more accordant with the results of the high-yield gas wells and the drilled core fracture description. References | Related Articles | Metrics

Identification of Sedimentary Microfacies in Retrograding Alluvial Fan of Badaowan Formation in Dishuiquan Oilfield in Eastern Junggar Basin WANG Jian-xin 2011, 32 (5):  489-491.  Abstract ( 95 )   PDF (582KB) ( 352 )   Save The studied results of regional geology, seismic, logging and core analysis data in the J1b1 sedimentary microfacies of the Badaowan formation in the Di-12 wellblock of Dishuiquan oilfield located in slope area of eastern Junggar basin show that the J1b1 is alluvial fan deposit, which could be further divided into 3 sub-facies of the top fan, middle fan, edge fan and 8 microfacies. The vertical variation of lithology and lithofaceies reflect that the target zone with the backfill characteristic on the Carboniferous is the earliest lowstand system tract of the Jurassic in this study area. The sedimentary environment of the J1b1 is transited from the top, middle fans up to the edge fan, showing such a period is in retrograding alluvial fan deposit under transgression environment. The identification of alluvial fan sedimentation microfacies of the Badaowan formation in Dishuiquan oilfield has a reference to prospecting the reservoirs related with the fans in eastern Junggar basin. References | Related Articles | Metrics

Analysis of Liquid-Carrying Capacity in High GLR Gas Wells with Downhole Choke LIU Yong-hui, ZHANG Zhong-bao, CHEN Ding-zhao, TANG Zhi-ping, HU Shi-qiang 2011, 32 (5):  495-497.  Abstract ( 123 )   PDF (258KB) ( 316 )   Save Aiming at the key problem whether liquid-carrying capacity is better or worse after applying the downhole choke than before, this article selects high gas-to-liquid ratio (GLR) gas well with downhole choke as research target. Taking downhole choke as a function node, its pressure drop correlation and temperature drop correlation are set up using the node analysis. The minimum flow rate for the continuous removal liquids by Professor Li Min is presented to quantitatively describe its liquid-carrying capacity and then obtain the minimum flow rate profile. The case analysis shows the minimum flow rate profile includes typical 3 parts in distribution and has 3 maximum rates. So the gas production rate should be higher than the maximum value of them. And the minimum flow rate between the reservoir and the downhole choke is higher than that between the downhole choke and the wellhead. In other words, the less gas rate with a downhole choke can help liquid-carrying production from gas well, which proves the liquid-carrying capacity is better than that without the downhole choke. But there is a maximum flow rate at the downhole choke, which proves the liquid-carrying capacity of the choke is worse for the bigger velocity difference between the gas jet and its surrounding mixture. References | Related Articles | Metrics

Study on Water Drive Characteristics of Vertical Injector-Fishbone Producer Well Pattern SUN Ming, YANG Zhi-dong, MA Yan-jun, HAN Ming-yi 2011, 32 (5):  498-500.  Abstract ( 118 )   PDF (426KB) ( 214 )   Save Fishbone well is of advantage for increasing the contact area of wellbore and reservoir and effectively improving development effect of low permeability fractured reservoirs. But affected by the well-type structure, the well pattern, etc., its water drive characteristic is complex and presents many problems, for instance, the water breakthrough time is difficult to determine and the water cut rises quickly. Based on numerical simulation technique, this paper presents the water drive development effect of low permeability fractured reservoir with vertical injector plus fishbone producer well pattern, including drawing water flood streamline distribution and water cut changing chart, and summarizes the regularity of the water cut rising by using such a pattern, being of a certain significance to actual reservoir development. References | Related Articles | Metrics

Catalytic Upgrading Experiment for Heavy Oil Viscosity Reduction under Steam Injection Process ZHANG Bo, LIU Yong-jian, ZHAO Fa-jun, HU Shao-bin 2011, 32 (5):  501-503.  Abstract ( 110 )   PDF (204KB) ( 290 )   Save This paper studied the self-made organic oil soluble nickel salt as a catalyst by which the aquathermolysis reaction of heavy oil is conducted using high temperature autoclave, and investigates the effects of catalyst requirement, reaction temperature, reaction time and injected water on the heavy oil viscosity and group composition before and after such a reaction, and then selects the optimum reaction condition for the viscosity reduction. Based on this condition, the heavy oil element before and after that is analyzed. The results show that after 24 h reaction and adding 0.1wt% catalyst of organic acids nickel, the viscosity of heavy oil decreased distinctly at reaction temperature of 240℃ and additive water amount of 30wt% , with the decreases of Asphaltene content by 1.4wt% , colloid content by 5.0wt%, and the increases of aromatic content by 3.5wt% and saturated component content by 2.9wt%. References | Related Articles | Metrics

Comparisons of Capillary Pressure Curves Between Low Permeability Sandstone and Micro-Fractured Marlstone ZANG Shi-bin, ZHENG Yong-xian, SUN Xi, XU Wen-mei, CHEN Yue-qing 2011, 32 (5):  504-507.  Abstract ( 103 )   PDF (402KB) ( 282 )   Save Usually, capillary pressure curve of sandstone is a smooth curve. However, the curve of marlstone with micro-fractures consists of two parts: an oblique line and a flat one. So the parameters such as threshold pressure and mean throat radius gained from capillary pressure curves of marlstone cannot describe the pore structure properly. This paper mainly discusses and analyzes the difference of mercury injection curves between sandstone and marlstone, and proposes a concept of effective throat radius to describe the pore structure of marlstone with micro-fracture. The case study shows this method is better than before. References | Related Articles | Metrics

Downhole Aquathermolysis Technology of In-Situ Upgrading Heavy Oil for Enhancing Oil Recovery by Steam Stimulation Process ZHANG Xian, LIU Yong-jian 2011, 32 (5):  508-511.  Abstract ( 90 )   PDF (331KB) ( 328 )   Save Aiming at low final oil recovery of steam stimulation for recovering heavy oil, the laboratory experiments and field tests of downhole aquathermolysis for in-situ upgrading heavy oil technology were conducted to study how to improve the situation. The experimental results show that the reservoir minerals have catalytic effects on aquathermolysis of heavy oil, among which the catalytic effect of clay minerals on oil viscosity reduction is better than that of rock minerals, reaching more than 30%. The higher the content of clay minerals is in the reservoir, the more oil reduction can be obtained in aquathermolysis. After nickel sulfate and tetralin are injected as a plug before steam, the final oil recovery is 8.8% more than that of pure steam stimulation, the oil viscosity reduction rate can be increased by 51.7% , the contents of saturates and aromatics increased by 38.0 mg/g and 26.3 mg/g and the contents of resins and asphaltenes reduced by 41.9 mg/g and 41.1 mg/g, respectively. The field test results demonstrate that downhole aquathermolysis technology for in-situ upgrading heavy oil can prolong production period of steam stimulation, increase daily oil production rate, control total water-cut, and increase oil/steam ratio and water recovery ratio. In the end, the development effect of steam stimulation will be largely improved. References | Related Articles | Metrics

Using Tracer to Study Interwell Water Flow Predominant Channel WANG Yu-qin, CHEN Fang-hong, GU Hong-jun, ZHOU Hui-ze, NIE Zhen-rong, LIU Fu-kui, LU Ming-hui 2011, 32 (5):  512-514.  Abstract ( 124 )   PDF (295KB) ( 347 )   Save Taking the compound flood test area of District Mid-7 in Karamay oilfield as an example, the tracer monitoring is conducted in 10 well groups in this area by selecting 8 low-concentration tracers, and the curves for these tracers are matched and analyzed finely using Eclipse. Based on the characterized parameters such as mean yield, peak breakthrough velocity, permeability multiple, tracer peak characteristic, etc., the interwell water flow channel in the test area is divided into primary predominant channel, secondary channel and normal porosity one. It is suggested that for these three channels, strong, medium and weak profile controls are applied respectively, among which when the permeability multiple is close to 8, the weak profile control is made for the normal porosity channel. In addition, this paper presents the suggestions for profile control intensity and profile control agent requirements for each layer corresponding to each well group, according to the channel types and heterogeneous features in this area. References | Related Articles | Metrics

Optimization of Injection-Production Well Pattern for Thin and Bottom Water Reservoir in Narrow River Channel in Tanhai Area in Shengli Oilfield ZHAI Liang 2011, 32 (5):  515-517.  Abstract ( 103 )   PDF (595KB) ( 297 )   Save The thin and bottom water reservoir like Block Lao-68 in Shengli oilfield has more and more contributions in recent years to this oilfield in incremental reserves and production. But such a reservoir is commonly of features such as low water drive control level, low single well yield and low oil recovery. On the basis of the establishment of the geological model of this block, the injection-production well pattern is optimized by streamline model. By which the original geological model is re-corrected, and the key production parameters are optimized, thus providing the scientific basis for reasonable and efficient development of this reservoir. References | Related Articles | Metrics

Design and Practice of Heavy Oil Reservoir Developed by Fishbone Horizontal Drilling Process DU Xin-jun 2011, 32 (5):  518-519.  Abstract ( 120 )   PDF (109KB) ( 210 )   Save Liaohe oil field is rich in heavy oil resources, it is the largest heavy oil production base in china. In recent years, Liaohe oilfield produced its heavy oil with horizontal well technology, and achieved good results. In order to improve heavy oil recovery ratio, the well structure, drilling string, drilling fluid and operation programs in Du84-XingH238 fishbone horizontal well was designed and optimized. The final effect evaluation result indicates that the fishbone horizontal well is more effective than normal horizontal well for exploitation of heavy oil and EOR. References | Related Articles | Metrics

Influencing Factors of CO2 Flooding in Low Permeability Reservoir with Reservoir Numerical Simulation LIAO Hai-ying, LV Cheng-yuan, ZHAO Shu-xia, CHEN Yan, HE Ying-fu, ZHOU Yin-bang, WANG Qiang 2011, 32 (5):  520-522.  Abstract ( 114 )   PDF (265KB) ( 481 )   Save Low-permeability oil reservoirs have unique features of low abundance, low pressure, and low yield, their economic and effective exploitation are very difficult. Gas injection is the more efficient recovery method for such reservoirs at home and abroad. With numerical simulator, the main influencing factors affecting CO2 flooding are determined, including analysis of the components of split and fitting, selection of state equation and experimental regression, etc. The study results show that phase behavior simulation is the key of success or failure in numerical simulation of compositional model. The mode of water-gas alternating injection, with properly increasing the injection pressure and selecting appropriate bottom-hole flowing pressure, has obvious effect on incremental production and EOR. Numerical simulation indicates that different well patterns or spacings, heterogeneity, fracture direction, gas injection parameters are the sensitive controlling factors of CO2 flooding, directly affecting reservoir development index and development effect. References | Related Articles | Metrics

Activating Test of Endogenous Microbes in Formation Water of District Mid-6 in Karamay Oilfield WANG Hong-bo, PENG Xiao-zhong, WU Yun-qiang, XU Guo-yong, WANG Yu-qin, DAI Xue-cheng 2011, 32 (5):  523-524.  Abstract ( 96 )   PDF (112KB) ( 263 )   Save The T2k1 reservoir in District mid-6 of Karamay field is a general heavy oil reservoir. The geological study showed that the reservoir conditions were suitable for the microbial growth, and the endogenous microbes in the produced water of the wells are abundant, with a good potential for the endogenous microbial flooding. In the activating field test of the endogenous microbes, the total bacteria concentration and the endogenous microbe numbers are increased by 1~3 magnitudes and 1~5 magnitudes, respectively. The concentrations of the acetate ions and bicarbonate ions in the produced fluid from the wells are increased substantially and obviously after the test. These indicate the endogenous microbes in the reservoir were activated distinctly, giving rise to very good activating effects. References | Related Articles | Metrics

Seismic Detection Method for Identification of Fractures in Fengcheng Dolomitic Limestone in Wuerhe-Xiazijie Fault Belt, Junggar Basin LEI De-wen, Abulimiti Yiming, WEN Xiao-tao, DING Jing, YAN Jian-guo, KONG Yu-hua 2011, 32 (5):  525-527.  Abstract ( 105 )   PDF (597KB) ( 317 )   Save Aiming at the dolomitic limestone fractured reservoir in the northwestern margin of Junggar basin, a series of the fractural detection methods are adopted, including the edge detection based on wavelet multiscale product, generalized Hilbert transform and curvature analysis. The model experiment shows that these methods are of high horizontal resolution and anti-noise ability. Applied to the first member of Fengcheng formation in Wuerhe-Xiazijie fault belt and by correlation analysis to regional structural characteristics and drilling/well data, it is indicated that these methods are applicable for this area. The three methods can be mutually confirmed and supplemented for the purpose of improving the reliability of the detection results. References | Related Articles | Metrics

Optimization of CO2 Huff and Puff Parameter of Heavy Oil Reservoirs ZHANG Chao-fu, LIU Bin, PU Yu-e, XU Ying, PAN You-jun 2011, 32 (5):  528-530.  Abstract ( 93 )   PDF (252KB) ( 272 )   Save CO2 huff and puff can drop oil viscosity, increase fluid mobility and make crude oil swell and oil compositions evaporate to increase oil production. Based on the characteristics of low fluid mobility reservoir in Wellblock Ma-46 in Niujuanhu and Mabei structural belts in northwestern Malang sag of Santanghu basin, combining reservoir engineering method with numerical simulation study, the feasibility of CO2 huff and puff in the reservoir is studied, the huff and puff parameters are optimized, the field test is conducted and evaluated, and good application effect is taken. References | Related Articles | Metrics

New Method for Diagnosing SAGD Production State in Condition of Artesian Flow SUN Xin-ge, ZHAO Rui, DU Wei-xing, ZHANG Jian-hua, REN Xiang 2011, 32 (5):  531-532.  Abstract ( 86 )   PDF (187KB) ( 200 )   Save Subcool is a conventional parameter, by which we can diagnose the state of steam assisted gravity drainage (SAGD) production, but this method extremely relies on the monitoring of temperature and pressure in wellbore. According to this, a new simplified method for the state diagnosing work is proposed, which can be a substitution for using the conventional subcool parameter. In the case study, just by using pressure in downhole and oil pressure at wellhead, the wellbore apparent density can be calculated in condition of artesian flow, which is the same as the function of subcool production state diagnosing. The case study of I well group in SAGD pilot test area of Xinjiang Fengcheng oilfield indicates that it is of a good guiding effect in the field heavy oil production and control. References | Related Articles | Metrics

Technique and Application of Anisotropic Prestack Migration TIAN Yan-can, ZENG Hua-hui, LU Lie-qin, YUAN Gang, QIE Shu-hai, ZHANG Tao 2011, 32 (5):  533-536.  Abstract ( 135 )   PDF (415KB) ( 341 )   Save The carbonate rocks in Tarim basin are of the obvious anisotropy. Using the conventional isotropic migration method may not only result in error of imaging position, but also affect the quality of seismic imaging, the precision of time-depth transformation and AVO analysis, etc. Taking the actual seismic data of carbonate rocks in Tarim basin as an example, this paper mainly discussed the anisotropic prestack migration technique, the method for evaluating anisotropic parameters and the processing flow of anisotropic prestack migration. The more accurate anisotropic velocity and the preserved abundant far-offset trace information allowed the precision of migration velocity and migration operator to be improved by evaluating the more accurate migration velocity field and reserving far-offset trace information. At the same time, the seismic imaging quality of the carbonate rocks can be effectively increased, and the "bead" reflectance, the faults and the break points appeared more clearly, thus providing a better gather for AVO inversion and the precision of reservoir description. References | Related Articles | Metrics

Prestack Bin Stack Imaging Principle and Application SHI Xing, ZHANG Xu-jian, LIANG Ying 2011, 32 (5):  537-540.  Abstract ( 135 )   PDF (465KB) ( 375 )   Save With the development of geophysical prospecting technologies, the complex structure and deep Carboniferous become one of favorable areas for petroleum exploration in Junggar basin. However, the imaging quality is often difficult to satisfy the requirement for petroleum exploration due to low signal-to-noise ratio of the seismic profiles in these areas caused from complicated surface and deep burial conditions. Increasing the imaging precision is an urgent task. Using the common reflection surface stack technology (CRS) can obtain higher signal-to-noise ratio than conventional stack profile, particularly, has a certain effect in improving complex structure continuity. In addition, integrated with prestack migration technology in seismic profile processing, CRS is one of effective methods for increasing the information quality. References | Related Articles | Metrics

Application of Kirchhoff Prestack Time Migration to Kuqa Mountain Land LI Dao-shan, CHENG Jian-bing, XIE Hui-wen, MA Feng-chen, WU Chao, SI Gang-yuan 2011, 32 (5):  541-543.  Abstract ( 105 )   PDF (825KB) ( 268 )   Save Prestack deep migration (PDM) as the best way to solve the accurate imaging of complex structures in Kuqa mountain land requires high precision in velocity, so the imaging quality of PDM is normally unsatisfactory in the condition of an inaccurate velocity model and low S/N. It is indispensable for using prestack time migration (PTM) data to guide the structural understandings in this area. The key point of Kirchhoff prestack time migration technology applied to Kuqa mountain land is the estimation of seismic travel time and the accurate solution of root-mean-square velocity on the relief surface. The former includes calculation of the time t0 of each imaging point and the travel time of shot-to-geophone points in the imaging point’s gather from the near-surface, and the latter includes the fine velocity analysis and the velocity scanning. By using this method, good imaging effects are obtained in actual seismic data processing from Kuqa mountain land, and worth further researching and generalizing. References | Related Articles | Metrics

The Seismic Method for Improving Accuracy of Trap Identification—An example from Karamay-Baikouquan fault belt in Karamay oilfield WU Cai-xi, PAN Li-jun, QI Yan-ping, WANG Ze-sheng 2011, 32 (5):  544-546.  Abstract ( 114 )   PDF (761KB) ( 195 )   Save Reliable trap identification of complex structures depends on migration imaging precision of the seismic data, and the reliable migration imaging depends on the migration velocity field developed whether to be consistent with the geological interpretation model or not. Prestack time migrated is based on high-precision migration velocity which can constrain geological structure model. Taking the sedimentary evolution of complex structures in the study area into account, this paper presents a reasonable geological structure model and the corresponding migration velocity field. According to Snell's law, the prestack time migration processing to the 3-D seismic data is conducted, obtaining a more reliable migration imaging, finding out five fault stractigraphic traps among which one is a stratigraphic trap, describing 3 fan bodies of Xiazijie formation of the Permian. Good effects of seismology and geology are gained. References | Related Articles | Metrics

Application of High-Temperature Enzyme Breaker to Fracturing Fluid in Karamay Oilfield ZHANG Tian-xiang, PAN Jing-jun, YANG Ping, MEI Xiao-dan 2011, 32 (5):  547-549.  Abstract ( 146 )   PDF (247KB) ( 236 )   Save Karamay field fracturing fluid system occurs in the problems of incomplete guar gum breaking and oil layer damage. The study showed that the high-temperature enzyme breaker had incompatibility with additives of the Karamay fracturing fluid system. The fracturing fluid viscosity can be reduced to 3.3 mPa·s within 2.5 h by adding 250 mg/L enzyme breaker, 250 mg/L protective agent and 0.01% ammonium persulfate, and the residue of 280 mg/L, which meet the national standards of an oilfield. The molecular weight of the fracturing fluid was measured by mass spectrometry, which was mainly concentrated in the range of 2 147~6 366 Da, indicating that the enzyme breaker can be used to decrease the viscosity of fracturing fluid and degrades gum to oligosaccharides. References | Related Articles | Metrics

The Formation Adaptability of Underbalanced Drilling Process JIN Ye-quan, LIU Gang, FANG Chuan-xin, WANG Mao-lin, SUN Zhe-qiu 2011, 32 (5):  550-551.  Abstract ( 101 )   PDF (110KB) ( 274 )   Save The unreasonable formation evaluation often causes inappropriate choices of underbalanced drilling, resulting in some complex situations and severe damages of reservoir. Also, for its large equipment and high moving cost, significant economic loss will be made. Based on large amounts of underbalanced drilling site statistics, this paper presents the evaluations of underbalanced drilling adaptability to formation, including contents and procedures. References | Related Articles | Metrics

The Research Progress of Hydrogen Sulfide Genesis in Gas Reservoir ZHAO Xing-qi, CHEN Jian-fa, ZHANG Chen, WU Xue-fei, LIU Ya-zhao, XU Xue-min 2011, 32 (5):  552-556.  Abstract ( 166 )   PDF (259KB) ( 368 )   Save Hydrogen sulfide is one of the common harmful non-hydrocarbon components which appear in marine carbonate gas reservoir. At present, it is generally believed that biological sulfate-reducing (BSR), thermochemical sulfate reduction (TSR) and thermal cracking of sulfocompound are the main causes of H2S in natural gas reservoirs. In addition, thermochemical sulfate reduction was thought to be the reason of reservoir with high content of H2S. According to the geological condition and geochemical characteristic in gas reservoir, it is easy to find out lots of evidences for the happening of thermal sulfate reduction, by which if the thermal sulfate reduction happened in a gas reservoir can be judged. However, there exist many problems to be solved in the researches on H2S in gas reservoirs ,including the genesis mechanisms, distribution pattern, characteristics of geology and geochemistry of hydrogen sulfide, as well as the relationship between hydrogen sulfide and hydrocarbon, the main controlling factors of forming hydrogen sulfide, etc. This paper summarizes the research progress on hydrogen sulfide genesis and existing issues at home and abroad, so that the hydrogen sulfide reservoirs could be more concerned. References | Related Articles | Metrics

Thinking on New Mode for Petroleum Exploration in Junggar Basin LIN Long-dong 2011, 32 (5):  557-563.  Abstract ( 83 )   PDF (867KB) ( 304 )   Save The Organic source sedimentary depression (sag) theory was on the whole unsuccessful in the process of guiding oil-gas geologic exploration in Junggar basin. This paper discusses the essential reasons for the unsuccess, and then puts forward a new mode for petroleum exploration in this basin: not only regarding the sedimentary depression (sag), but also stressing whether the mantle-derived diapiric structures exist in lower crust or not, both of which should be treated as an inseparable unity. For supporting this new mode, nine evidences are listed. Finally, some ideas or methods for the future work and how to revitalize the potential petroleum resources in 50~60 basins of midwestern China are proposed. References | Related Articles | Metrics

An Approach to the Origin of Volcanoes HU Dao-xiong 2011, 32 (5):  564-568.  Abstract ( 175 )   PDF (222KB) ( 413 )   Save Volcano is one of exiting modalities of substances redistribution in the earth. The origin of volcano results from that the state of the mantle solid substance is changed, resulting in substances' differentiation. When it happens, displacement reaction of substances appears on top of the mantle. And then the load of displacement space will decrease, causing the buoyancy increasing. In the end, volcanic eruptions will happen. There are basic conditions for the formation of volcanoes, namely, displacement substances, displacement space and eruption channels. There are five existing states of volcanoes: perennial, intermittent, opening, ending and under-erupted ones, which are highly related with the velocity of substance displacement. And it keeps a close relationship with the velocity of solid substances' state change. Volcanic eruption results from substances emission in the earth, which can also cause volumetric change of the earth, namely crust movement. Intensity of volcanic eruption is in proportion to the thickness of the crust. If the crust is thinner, volcanic eruption can not happen but only overflow. And if the crust is thicker, greater pressure will produce in the displacement space. Pressure inside of the volcano is closely related with displacement height and density of the substance, by which the pressure can be calculated. Distributions of volcanoes are also interrelated to the distribution of solid substances of the mantle. And the distribution of the volcanoes in geohistory periods is strongly affected by the degree of impinging planetesimals, and that in later periods is mainly affected by subducted plates. References | Related Articles | Metrics

Formation and Distribution of Giant Oil and Gas Fields in the South Caspian Basin GAO Min, HE Deng-fa 2011, 32 (5):  569-574.  Abstract ( 184 )   PDF (702KB) ( 457 )   Save Based on the data from the 15 giant fields and by means of petroleum system analytical method, the tectonic and depositional evolutions and petroleum geologic conditions in the South Caspian basin are discussed. The research shows that most reserves of the basin are from the Maykop-Red Bed petroleum system, the large-sized strike-slip compaction structural belt in northern margin of this basin is in the most advantageous petroleum geologic conditions. The giant fields that have been found are typically located in this the structural belt. The fold belts along both the west and the east coastlines of the Caspian alo have good petroleum geologic conditions of source, reservoir and cap rocks, being helpful to be the favorable areas for future exploration. The Maykop-Red Bed formation is a young petroleum system, the generation and migration and accumulation of the hydrocarbon are still active. So, even the structural belt with high degrees of exploration in the northern margin of this basin still has a greater potential for petroleum exploration. References | Related Articles | Metrics