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| 1 | Distribution and genesis of the anomalously high porosity zones in the middle-shallow horizons of the northern Songliao Basin显示文摘High-quality reservoirs occur in the middle-shallow horizons of the northern Songliao Basin. The distribution and genesis of their anomalously high porosity zones were studied using measured porosities, examination of ordinary thin sections and blue epoxy resin-impregnated thin sections and by SEM. The results show that there are three anomalously high porosity zones at the depth of 450-900 m, 1,300-1,900 m, 2,050-2,350 m respectively, named zone i, zone ii and zone iii from top to bottom. Horizontally, zone i and zone ii are distributed all over the basin except in the Southeastern Uplift, while zone iii is only distributed in the Central Depression. Zone i was formed by meteoric water leaching as well as organic acid dissolution. Zones ii and iii were dominantly formed by organic acid dissolution. Additionally, clay mineral transformation generating H+ and hydrocarbon emplacement retarding the cementation of sandstones are also important for the formation of zones ii and iii. | Meng Yuanlin Liang Hongwei Meng Fanjin Wu Heyong Wang Cheng Xiu Hongwen Zhang Anda Li Yaguang Guo Rixin | 2010 | Petroleum Science2010,7,3: | 29 |
| 2 | Coalbed methane genesis, occurrence and accumulation in China显示文摘Coalbed methane (CBM) is an important type of unconventional gas. Commercial development of CBM in America has been very successful since the 1980s. The CBM industry in Australia and Canada has developed rapidly during the last decade. Commercial development of CBM in China started in the 1990s, and has made great progress. The geological theory of CBM in China has achieved great advancement in genesis, occurrence and accumulation. On the aspect of CBM genesis, five CBM genetic types (primary biogenic gas, secondary biogenic gas, thermal degradation gas, pyrolysis gas and mixed gas) are identified by studying the geochemical characteristics of CBM, and a tracing indicator system is established. The discovery of secondary biogenic gas in medium-high rank coal reservoirs has widened the potential of CBM resources. On the aspect of CBM occurrence, the gas adsorption regulation under combined action of temperature and pressure is revealed by conducting adsorption experiments of different coal ranks under varying temperature and pressure conditions. Besides, by applying the adsorption potential theory in CBM research, the adsorption model under combined action of temperature and pressure is established. The new model can predict CBM resources accurately, and overcome the limitation of the traditional Langmuir model which uses just a single factor to describe the adsorption characteristics of deep buried coal. On the aspect of CBM accumulation, it is proposed that there are three evolutionary stages during CBM accumulation, including gas generation and adsorption, unsaturated gas adsorption, gas desorption-diffusion and preservation. Controlled by tectonic evolution, hydrodynamics and sealing conditions, CBM tends to be regionally enriched in synclines. Advances in geological theory of CBM in China can not only improve understanding of natural gas, but also provide new ideas for further exploration of CBM. | Song Yan Liu Shaobo Zhang Qun Tao Mingxin Zhao Mengjun Hong Feng | 2012 | Petroleum Science2012,9,3: | 29 |
| 3 | Petroleum geology features and research developments of hydrocarbon accumulation in deep petroliferous basins显示文摘As petroleum exploration advances and as most of the oil–gas reservoirs in shallow layers have been explored, petroleum exploration starts to move toward deep basins, which has become an inevitable choice. In this paper, the petroleum geology features and research progress on oil–gas reservoirs in deep petroliferous basins across the world are characterized by using the latest results of worldwide deep petroleum exploration. Research has demonstrated that the deep petroleum shows ten major geological features.(1) While oil–gas reservoirs have been discovered in many different types of deep petroliferous basins, most have been discovered in low heat flux deep basins.(2) Many types of petroliferous traps are developed in deep basins, and tight oil–gas reservoirs in deep basin traps are arousing increasing attention.(3) Deep petroleum normally has more natural gas than liquid oil, and the natural gas ratio increases with the burial depth.(4) The residual organic matter in deep source rocks reduces but the hydrocarbon expulsion rate and efficiency increase withthe burial depth.(5) There are many types of rocks in deep hydrocarbon reservoirs, and most are clastic rocks and carbonates.(6) The age of deep hydrocarbon reservoirs is widely different, but those recently discovered are predominantly Paleogene and Upper Paleozoic.(7) The porosity and permeability of deep hydrocarbon reservoirs differ widely, but they vary in a regular way with lithology and burial depth.(8) The temperatures of deep oil–gas reservoirs are widely different, but they typically vary with the burial depth and basin geothermal gradient.(9) The pressures of deep oil–gas reservoirs differ significantly, but they typically vary with burial depth, genesis, and evolution period.(10) Deep oil–gas reservoirs may exist with or without a cap, and those without a cap are typically of unconventional genesis. Over the past decade, six major steps have been made in the understanding of deep hydrocarbon reservoir formation.(1) Deep petroleum in petroliferous basins has multiple sources and many different genetic mechanisms.(2) There are high-porosity,high-permeability reservoirs in deep basins, the formation of which is associated with tectonic events and subsurface fluid movement.(3) Capillary pressure differences inside and outside the target reservoir are the principal driving force of hydrocarbon enrichment in deep basins.(4) There are three dynamic boundaries for deep oil–gas reservoirs; a buoyancy-controlled threshold, hydrocarbon accumulation limits, and the upper limit of hydrocarbon generation.(5)The formation and distribution of deep hydrocarbon reservoirs are controlled by free, limited, and bound fluid dynamic fields. And(6) tight conventional, tight deep, tight superimposed, and related reconstructed hydrocarbon reservoirs formed in deep-limited fluid dynamic fields have great resource potential and vast scope for exploration.Compared with middle–shallow strata, the petroleum geology and accumulation in deep basins are morecomplex, which overlap the feature of basin evolution in different stages. We recommend that further study should pay more attention to four aspects:(1) identification of deep petroleum sources and evaluation of their relative contributions;(2) preservation conditions and genetic mechanisms of deep high-quality reservoirs with high permeability and high porosity;(3) facies feature and transformation of deep petroleum and their potential distribution; and(4) economic feasibility evaluation of deep tight petroleum exploration and development. | Xiong-Qi Pang Cheng-Zao Jia Wen-Yang Wang | 2015 | Petroleum Science2015,12,1: | 27 |
| 4 | Main controlling factors and enrichment area evaluation of shale gas of the Lower Paleozoic marine strata in south China显示文摘The Lower Paleozoic shale in south China has a very high maturity and experienced strong tectonic deformation. This character is quite different from the North America shale and has inhibited the shale gas evaluation and exploration in this area. The present paper reports a comprehensive investigation of maturity, reservoir properties,fluid pressure, gas content, preservation conditions, and other relevant aspects of the Lower Paleozoic shale from the Sichuan Basin and its surrounding areas. It is found that within the main maturity range(2.5 %3.5 %) is considered a high risk for shale gas exploration. Taking the southern area of the Sichuan Basin and the southeastern area of Chongqing as examples of uplifted/folded and faulted/folded areas, respectively, geological models of shale gas content and loss were proposed.For the uplifted/folded area with a simple tectonic deformation, the shale system(with a depth >2000 m) has largely retained overpressure during uplifting without a great loss of gas, and an industrial shale gas potential is generally possible. However, for the faulted/folded area with a strong tectonic deformation, the sealing condition of the shalesystem was usually destroyed to a certain degree with a great loss of free gas, which decreased the pressure coefficient and resulted in a low production capacity. It is predicted that the deeply buried shale(>3000 m) has a greater gas potential and will become the focus for further exploration and development in most of the south China region(outside the Sichuan Basin). | Xian-Ming Xiao Qiang Wei Hai-Feng Gai Teng-Fei Li Mao-Lin Wang Lei Pan Ji Chen Hui Tian | 2015 | Petroleum Science2015,12,4: | 27 |
| 5 | Synthesis and evaluation of an oil-soluble viscosity reducer for heavy oil显示文摘To reduce the viscosity of highly-viscous oil of the Tahe oilfield (Xinjiang,China),an oilsoluble polybasic copolymer viscosity reducer for heavy oil was synthesized using the orthogonal method.The optimum reaction conditions are obtained as follows:under the protection of nitrogen,a reaction time of 9 h,monomer mole ratio of reaction materials of 3:2:2 (The monomers are 2-propenoic acid,docosyl ester,maleic anhydride and styrene,respectively),initiator amount of 0.8% (mass percent of the sum of all the monomers) and reaction temperature of 80 oC.This synthesized viscosity reducer is more effective than commercial viscosity reducers.The rate of viscosity reduction reached 95.5% at 50 oC.Infrared spectra (IR) and interfacial tensions of heavy oil with and without viscosity reducer were investigated to understand the viscosity reduction mechanism.When viscosity reducer is added,the molecules of the viscosity reducer are inserted amongst the molecules of crude oil,altering the original intermolecular structure of crude oil and weakening its ability to form hydrogen bonds with hydroxyl or carboxyl groups,so the viscosity of crude oil is reduced.Field tests of the newly developed oil-soluble viscosity reducer was carried out in the Tahe Oilfield,and the results showed that 44.5% less light oil was needed to dilute the heavy oil to achieve the needed viscosity. | Guo Jixiang Wang Heyi Chen Chaogang Chen Yun Xie Xiaohai | 2010 | Petroleum Science2010,7,4: | 24 |
| 6 | Strain-based design for buried pipelines subjected to landslides显示文摘Landslides are one of the key problems for stability analysis of pipelines in the western region of China where the geological conditions are extremely complicated. In order to offer a theoretical basis for the pipe-soil interaction, the general finite element program ABAQUS is used to analyze the distribution of pipe strain caused by landslide through which the pipeline passes. In this paper the Ramberg-Osgood constitutive equation is used to study the strain-based mechanical characteristics of pipelines. Different calculation schemas are designed by considering the change of spatial relationship between pipeline and landslide, and the change of D/t, diameter-thickness ratio of pipeline. The results indicate that the pipeline is primarily subjected to tension stress when the landslide crosses the pipeline perpendicularly, the pipe strain is a maximum along the central axis of the landslide, and reverse bending occurs on pipeline at both edges of the landslide. The pipeline is primarily subjected to friction force caused by the downward movement of the landslide, and the friction force is relatively small when the landslide is parallel to the pipeline. The pipe strain is in proportional to D/t, and this means decreasing D/t can help to improve security of pipelines subjected to the landslide. | Han Bing Wang Zhiyin Zhao Honglin Jing Hongyuan WuZhangzhong | 2012 | Petroleum Science2012,9,2: | 22 |
| 7 | Using the curve moment and the PSO-SVM method to diagnose downhole conditions of a sucker rod pumping unit显示文摘Downhole working conditions of sucker rod pumping wells are automatically identified on a computer from the analysis of dynamometer cards. In this process, extraction of feature parameters and pattern classification are two key steps. The dynamometer card is firstly divided into four parts which include different production information according to the 'four point method' used in actual oilfield production, and then the moment invariants for pattern recognition are extracted. An improved support vector machine (SVM) method is used for pattern classification whose error penalty parameter C and kernel function parameter g are optimally chosen by the particle swarm optimization (PSO) algorithm. The simulation results show the method proposed in this paper has good classification results. | Li Kun Gao Xianwen Tian Zhongda Qiu Zhixue | 2013 | Petroleum Science2013,10,1: | 23 |
| 8 | Resource Potential and Exploration Techniques of Stratigraphic and subtle Reservoirs in China显示文摘The onshore oil and gas exploration has stepped into a new stage in China, with equal attention paid to both stratigraphic and subtle reservoirs and structural reservoirs. In the past few years, the increases in oil reserves in most basins were found mainly in the stratigraphic and subtle reservoirs. Latest resource evaluation shows that the onshore stratigraphic and subtle reservoirs in China account for 42% of the total remaining resource, the highest in the four major exploration regions. Therefore, these reservoirs will be the most practical, potential and prevalent fields for long-lasting oil and gas exploration in onshore China. Among PetroChina's annual oil geologic reserves of 4.3 X 10sty4.6 X 10st, the stratigraphic and subtle reservoirs account for more than 50%. In such basins as Songliao, Ordos, Bohai Bay, Junggar, Tarim, Sichuan and Erlian basins, stratigraphic and subtle reservoirs with geologic reserves ranging from 5 X 107t to 3 X 10st were discovered, including Ansai, Jing'an, Daqingzijing, Liuxi, well-21 area in Shinan, and Hadexun. Stratigraphic and subtle reservoirs in the four types of inland basins differ from each other in the formation conditions and the distribution patterns. While continental basins are controlled by unconformity surface, maximum flooding surface and fracture surface, the Paleozoic marine basins are influenced by paleouplift, unconformity surface, and fluctuation of the sea level. Through exploration practices and research, PetroChina has formed its own technique series focused on 3-D seismics and sequence stratigraphy. | JiaChengzao ChiYingliu | 2004 | Petroleum Science2004,1,2: | 23 |
| 9 | Diagenesis and Its Effect on Reservoir Quality of Silurian Sandstones,Tabei Area,Tarim Basin,China显示文摘The diagenetic processes of the Tabei sandstones in the Tarim Basin include compaction, cementation (quartz overgrowths, calcite, clay minerals and a minor amount of pyrite), and dissolution of the feldspar and calcite cement. Porosity was reduced by compaction from an assumed original 40% to about 22.1%. Cementation reduced porosity to 26.6%. The Tabei sandstones lost a little more porosity by compaction than by cementation. Quartz cementation, especially syntaxial quartz overgrowth, is a major cause of porosity-loss in many reservoirs in moderately to deeply buried sandstone. Calcite cementation played a key role in the porosity evolution of sandstones. At the early stage of burial, the early calcite cement occupied most of the pore spaces resulting in significant porosity. On the other hand, some primary porosity has been preserved due to incomplete filling or the presence of scattered patches of calcite cement. In addition to calcite, several clay minerals, including illite and chlorite occurred as pore-filling and pore-lining cements. The pore-lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial quartz overgrowths. Illite, which largely occurred as hair-like rims around the grains and bridges on the pore throats, caused a substantial deterioration of penetrability of the reservoir. Calcite cement dissolution was extensive and contributed significantly to the development of secondary porosity. | Zhang Jinliang Jia Ying Du Guilin | 2007 | Petroleum Science2007,4,3: | 21 |
| 10 | Quantitative evaluation methods for waterflooded layers of conglomerate reservoir based on well logging data显示文摘The rapid changing near source, multi-stream depositional environment of conglomerate reservoirs leads to severe heterogeneity, complex lithology and physical properties, and large changes of oil layer resistivity. Quantitative evaluation of water-flooded layers has become an important but difficult focus for secondary development of oilfields. In this paper, based on the analysis of current problems in quantitative evaluation of water-flooded layers, the Kexia Group conglomerate reservoir of the Sixth District in the Karamay Oilfield was studied. Eight types of conglomerate reservoir lithology were identified effectively by a data mining method combined with the data from sealed coring wells, and then a multi-parameter model for quantitative evaluation of the water-flooded layers of the main oil-bearing lithology was developed. Water production rate, oil saturation and oil productivity index were selected as the characteristic parameters for quantitative evaluation of water-flooded layers of conglomerate reservoirs. Finally, quantitative evaluation criteria and identification rules for water-flooded layers of main oil-bearing lithology formed by integration of the three characteristic parameters of water-flooded layer and undisturbed formation resistivity. This method has been used in evaluation of the water-flooded layers of a conglomerate reservoir in the Karamay Oilfield and achieved good results, improving the interpretation accuracy and compliance rate. It will provide technical support for avoiding perforation of high water-bearing layers and for adjustment of developmental programs. | Tan Fengqi Li Hongqi Xu Changfu Li Qingyuan Peng Shouchang | 2010 | Petroleum Science2010,7,4: | 21 |
| 11 | Study on Relationship between Microstructure of Active Phase and HDS Performance of Sulfided Ni-Mo Catalysts: Effect of Metal Loading显示文摘Six Ni-Mo catalysts with different metal contents were prepared and characterized by N2 adsorption and X-ray diffractometry. The active phase microstructure of these catalysts was examined by the Raman spectroscopy, temperatureprogrammed reduction(TPR), X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Hydrodesulfurization(HDS) activity of catalyst samples were analyzed in a flow fixed-bed microreactor. The sulfidation degree of Mo and the length of the MoS2 slab slightly increased with the amount of metal loaded following sulfidation. This small change is attributed to polymolybdate species observed in all the oxidized catalysts. Weak metal-support interactions, as determined by the TPR technique, increased the NiSx sulfidation phase and MoS2 slab stacking. The HDS activity of the catalyst samples increased with the number of active sites. For high metal loading catalysts, their HDS activity was nearly identical because the sulfur atoms cannot easily approach active sites. This change is caused by the large number of stacked layers in the MoS2 slabs as well as the decrease in the specific surface area and pore volume of the catalyst samples with an increasing metal loading. | Guo Rong Shen Benxian Fang Xiangchen Sun Jin Peng Chong Cui Xiaoli | 2014 | China Petroleum Processing & Petrochemical Technology2014,16,2: | 21 |
| 12 | Formation and destruction processes of upper Sinian oil-gas pools in the Dingshan-Lintanchang structural belt, southeast Sichuan Basin, China显示文摘The lower Cambrian Niutitang Formation hydrocarbon source rocks at the Dingshan-Lintanchang structure in the southeast Sichuan Basin were of medium-good quality with two excellent hydrocarbon-generating centers developed in the periphery areas, with a possibility of forming a medium to large-sized oil-gas field. Good reservoir rocks were the upper Sinian (Dengying Formation) dolomites. The mudstone in the lower Cambrian Niutitang Formation with a good sealing capacity was the cap rock. The widely occurring bitumen in the Dengying Formation indicates that a paleo oil pool was once formed in the study area. The first stage of paleo oil pool formation was maturation of the lower Cambrian source rocks during the late Ordovician. Hydrocarbon generation from the lower Cambrian source rocks stopped due to the Devonian-Carboniferous uplifting. The lower Cambrian source rocks then restarted generation of large quantities of hydrocarbons after deposition of the middle Permian sediments. This was the second stage of the paleo oil pool formation. The oil in the paleo oil pool began to crack during the late Triassic and a paleo gas pool was formed. This paleo gas pool was destroyed during the Yanshan-Himalayan folding, uplifting and denudation. Bitumen can be widely seen in the Dengying Formation in wells and outcrops in the Sichuan Basin and its periphery areas. This provides strong evidence that the Dengying Formation in the Sichuan Basin and its periphery areas was once an ultra-large structural-lithologic oil-gas field, which was damaged during the Yanshan-Himalayan period. | Liu Shugen Zhang Zhijing Huang Wenming Wang Guozhi Sun Wei Xu Guosheng Yuan Haifeng Zhang Changjun Deng Bin | 2010 | Petroleum Science2010,7,3: | 20 |
| 13 | Numerical simulation of gas transport mechanisms in tight shale gas reservoirs显示文摘Due to the nanometer scale pore size and extremely low permeability of a shale matrix,traditional Darcy's law can not exactly describe the combined gas transport mechanisms of viscous flow and Knudsen diffusion.Three transport models modified by the Darcy equation with apparent permeability are used to describe the combined gas transport mechanisms in ultra-tight porous media,the result shows that Knudsen diffusion has a great impact on the gas transport and Darcy's law cannot be used in a shale matrix with a pore diameter less than 1 μm.A single porosity model and a double porosity model with consideration of the combined gas transport mechanisms are developed to evaluate the influence of gas transport mechanisms and fracture parameters respectively on shale gas production.The numerical results show that the gas production predicted by Darcy's law is lower than that predicted with consideration of Knudsen diffusion and the tighter the shale matrix,the greater difference of the gas production estimates.In addition,the numerical simulation results indicate that shale fractures have a great impact on shale gas production.Shale gas cannot be produced economically without fractures. | Yao Jun Sun Hai Fan Dong-yan Wang Chen-chen Sun Zhi-xue | 2013 | Petroleum Science2013,10,4: | 20 |
| 14 | Status quo of soil petroleum contamination and evolution of bioremediation显示文摘Along with the rapid development of oil industries internationally,petroleum prospecting and exploitation activities are growing intensively.Especially in China,with the fastest economic growth in the world and shortage of petroleum resources,we are leading the practices of petroleum deep exploitation.Obviously,the risk of damage to the natural environment from these activities is high.Oil contamination in soils and groundwater is becoming a big issue along with pesticide pollution,which makes organic pollution prevention and control (OPPC) much more complex.In this paper,based on recent research on oil-contaminated soil at home and abroad,we make comments on the remediation technologies for polluted soil,emphasizing bioremediation techniques and degradation mechanisms in order to push forward research into bound organic pollution prevention and control (OPPC),especially in China. | Du Weidong Wan Yunyang Zhong Ningning Fei Jiajia ZhangZhihuan Chen Lijun Hao Jiming | 2011 | Petroleum Science2011,8,4: | 19 |
| 15 | Research on in-situ condition preserved coring and testing systems显示文摘As shallow resources are increasingly depleted,the mechanics'theory and testing technology of deep insitu rock has become urgent.Traditional coring technologies obtain rock samples without retaining the in-situ environmental conditions,leading to distortion of the measured parameters.Herein,a coring and testing systems retaining in-situ geological conditions is presented:the coring system that obtains in-situ rock samples,and the transfer and testing system that stores and analyzes the rocks under a reconstructed environment.The ICP-Coring system mainly consists of the pressure controller,active insulated core reactor and insulation layer and sealing film.The ultimate bearing strength of 100 MPa for pressurepreservation,temperature control accuracy of 0.97%for temperature-retained are realized.CH_(4)and CO permeability of the optimized sealing film are as low as 3.85 and 0.33 ppm/min.The average tensile elongation of the film is 152.4%and the light transmittance is reduced to 0%.Additionally,the pressure and steady-state temperature accuracy for reconstructing the in-situ environment of transfer and storage system up to 1%and±0.2 is achieved.The error recorded of the noncontact sensor ring made of lowdensity polymer is less than 6%than that of the contact test.The system can provide technical support for the deep in-situ rock mechanics research,improving deep resource acquisition capabilities and further clarifying deep-earth processes. | He-Ping Xie Tao Liu Ming-Zhong Gao Ling Chen Hong-Wei Zhou Yang Ju Feng Gao Xiao-Bo Peng Xiong-Jun Li Rui-Dong Peng Ya-Nan Gao Cong Li Zhi-Qiang He Ming-Qing Yang Zhi-Yu Zhao | 2021 | Petroleum Science2021,18,6: | 19 |
| 16 | Hydraulic fracture initiation theory for a horizontal well in a coal seam显示文摘A series of experiments were performed to determine rock mechanical parameters related to hydraulic fracturing of coal.The effect of confining pressure and pore pressure on the strength of coal was studied.Experimental results show that the coal seam in the study areas has a relatively low elastic modulus,high Poisson's ratio,high fragility and is easily broken and compressed.The coal seam is considered as a transversely isotropic medium,since the physical properties in the direction of bedding plane and orthogonal to the bedding plane vary markedly.Based on the generalized plane strain model,stress distribution for an arbitrarily orientated wellbore in the coal seam was determined.In a horizontal well,hydraulic fracturing was found to initiate in the coal seam mass due to tensile failure,or from cleats due to shear or tensile failure.For those coal seams with abundant natural cleats,hydraulic fracture initiation can be induced by any of these mechanisms.In this study,hydraulic fracture initiation criteria for a horizontal well in a coal seam were established. | Hou Bing Chen Mian Wang Zheng Yuan Jianbo Liu Ming | 2013 | Petroleum Science2013,10,2: | 18 |
| 17 | The influence of DC stray current on pipeline corrosion显示文摘DC stray current can cause severe corrosion on buried pipelines.In this study,firstly,we deduced the equation of DC stray current interference on pipelines.Next,the cathode boundary condition was discretized with pipe elements,and corresponding experiments were designed to validate the mathematical model.Finally,the numerical simulation program BEASY was used to study the corrosion effect of DC stray current that an auxiliary anode bed generated in an impressed current cathodic protection system.The effects of crossing angle,crossing distance,distance of the two pipelines,anode output current,depth,and soil resistivity were investigated.Our results indicate that pipeline crossing substantially affects the corrosion potential of both protected and unprotected pipelines.Pipeline crossing angles,crossing distances,and anode depths,our results suggest,have no significant influence.Decreasing anode output current or soil resistivity reduces pipeline corrosion gradually.A reduction of corrosion also occurs when the distance between two parallel pipelines increases. | Gan Cui Zi-Li Li Chao Yang Meng Wang | 2016 | Petroleum Science2016,13,1: | 18 |
| 18 | Prediction of casing wear in extended-reach drilling显示文摘Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to energy principle and dynamic accumulation of casing wear by tool joints, a model is established to calculate the wear area on the inner wall of the casing. The relationship functions between the wear groove depth and area are obtained based on the geometry relationship between the drillstring and the wear section and the assumption that the casing wear groove is crescent-shaped. The change of casing wear groove depth versus drilling footage under different-sized drillstrings is also discussed. A mechanical model is proposed for predicting casing wear location, which is based on the well trajectory and drillstring movement. The casing wear groove depth of a planned well is predicted with inversion of the casing wear factor from the drilled well and necessarily revised to improve the prediction accuracy for differences between the drilled well and the planned well. The method for predicting casing wear in extended-reach drilling is verified through actual case study. The effect of drillstring size on casing wear should be taken into account in casing wear prediction. | Gao Deli Sun Lianzhong Lian Jihong | 2010 | Petroleum Science2010,7,4: | 18 |
| 19 | Characteristics and origin of abnormally high porosity zones in buried Paleogene clastic reservoirs in the Shengtuo area, Dongying Sag, East China显示文摘There are three abnormally high porosity zones developed in buried Paleogene nearshore subaqueous fan and sublacustrine fan clastic reservoirs at 2,800-3,200 m, 3,250-3,700 m and 3,900-4,400 m, respectively, within the Shengtuo area of the Dongying Sag. Here the porosity of reservoirs buried deeper than 4,000 m can still be greater than 20%. Investigation of these three abnormally high porosity(AHP) zones in the 3rd to 4th member of the Paleogene Shahejie Formation in the Shengtuo area was carried out with utilization of core observation, thin section identification, SEM observation, image analysis, core physical property testing and other technical methods. The results show that, the AHP zones in 2,800-3,200 m and 3,250-3,700 m are visible pores primary AHP zones dominated by significant primary intergranular pores(more than 50% of the total porosity), while secondary pores and micropores in authigenic clays may develop in some reservoirs. AHP reservoirs in the AHP zone of 3,900-4,400 m are dominated by micropores in matrix, visible pores are mainly grain dissolution pores but with low absolute content(< 1%), so this zone belongs to the micropores primary AHP zone. The genesis of the three AHP zones was studied to distinguish between porosity enhancement and porosity preservation. Our research shows that, in deeply buried clastic reservoirs in the Shengtuo area, mineral dissolution occurred in a relatively closed diagenetic system with high temperature and high salinity. Reservoir rocks underwent extensive feldspar dissolution, while detrital carbonate grains and carbonate cements show no evidence of extensive dissolution. Although significant feldspar dissolution pores developed, feldspar dissolution enhanced porosity only a little due to the precipitation of almost isovolumetric dissolution products in the nearby primary intergranular pores in forms of authigenic clays and quartz cements. Net enhanced porosity originating from feldspar dissolution is generally less than 0.25%. Thus, the subsurface dissolution has little impact on the mid-deep buried high porosity reservoirs. Reservoirs in braided channels of middle fans in sublacustrine fans and reservoirs in the middle-front of fan bodies of nearshore subaqueous fans provide the basis for the development of AHP zones. The shallow development of fluid overpressure and early hydrocarbon emplacement have effectively retarded compaction and carbonate cementation, so that the high porosity in the superficial layers is preserved in the mid-deep layers. These are the main controlling factors in the development of AHP zones. | Cao Yingchang Yuan Guanghui Li Xiaoyan Wang Yanzhong Xi Kelai Wang Xiaoming Jia Zhenzhen Yang Tian | 2014 | Petroleum Science2014,11,3: | 18 |
| 20 | Wall Sticking of High Water-Cut, Highly Viscous and High Gel-Point Crude Oil Transported at Low Temperatures显示文摘Some crude oils with high water cut have the capability to flow below the oil gel point, while the oil particles adhere to the pipe wall in the form of paste, also called 'wall sticking'. Wall sticking is a serious problem during the pipeline transportation, leading to partial or total blockage of the pipeline and energy wastage. In this paper, a series of laboratory flow loop experiments were conducted to observe the wall sticking characteristics of crude oil with high water cut, high viscosity and high gel point at low transportation temperatures. The effects of shear stress and water cut on the wall sticking rate and occurrence temperature were investigated. Experimental results indicated that the wall sticking rate and occurrence temperature were lower under stronger shear stress and higher water cut conditions. A criterion of wall sticking occurrence temperature(WSOT) and a regression model of wall sticking rate were then established. Finally, the software was developed to calculate the pressure drop along the pipelines of crude oils with high water-cut. It was able to predict the wall sticking thickness of gelled oil and then calculate the pressure drop along the pipelines. A typical case study indicated that the prediction results obtained from the software were in agreement with actual measured values. | Zheng Haimin Huang Qiyu Wang Changhui Wang Xi | 2015 | China Petroleum Processing & Petrochemical Technology2015,17,4: | 17 |