, Volume 39 Issue 1

    

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综合研究
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  Key technologies and understandings on the construction of smart fields

  Jia Ailin and Guo Jianlin

  , 2012, 39(1): 1975-0.

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  This paper analyzes the main features, trends, solutions, construction elements of smart fields and the technical difference of smart fields at home and abroad. Smart fields include three elements: real-time monitoring, modeling, decision-making and implementation. Their main features are real time, integration and continuity. The essence of smart fields is the optimization based on the model system, including 4 levels: single-well optimization, production optimization, reservoir optimization and optimization of the overall assets. And the overall system optimization is the ultimate objective. For smart fields, the smart is a method of constructing smart fields and efficient development is its purpose. Data is the basis and key of smart fields. The essence of smart field decision-making is based on the model. Smart fields can’t go without the support of high-tech industry. The difference of smart fields technologies between home and abroad mainly lies in the oil and gas exploration and development mode and management concepts, technical means and research team, the timeliness of decision making, the responsibilities of different professionals and development objects.
油气勘探
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  Geological conditions and distributional features of large-scale carbonate reservoirs onshore China

  Zhao Wenzhi; Shen Anjiang; Hu Suyun; Zhang Baomin; Pan Wenqing; Zhou Jingao and Wang Zecheng

  , 2012, 39(1): 2001-0.

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  Based on the analysis and observation of well cores and thin sections of more than 300 wells from major exploration plays and intervals in the Tarim, Sichuan and Ordos Basins, and combined with seismic, well logging and testing data, this paper studies and analyses systematically on the types and characteristics of carbonate reservoirs as well as the geologic conditions for their development with large scale. And their distributional features are also summarized. All kinds of marine carbonate reservoirs revealed worldwide are developed onshore China, including 3 types of large-scale effective reservoirs, which are depositional reef-shoal and dolomite reservoirs, epigenetic dissolution-percolation reservoirs and deep burial-hydrothermally altered reservoirs. Besides sedimentary facies, paleoclimate and paleogeomorphy, other factors that have strong influences on the development of deep large-scale reservoirs include interstratal and intrastratal dissolution-percolation, burial dolomitization combined with hydrothermal processes, etc. Large-scale effective reservoirs in deep carbonate sequence are mostly well distributed along the unconformities and hiatuses in sedimentational sequences, while reservoirs with epigenetic dissolution-percolation origion are well occurred from the paleo-uplift highs to the lower part of slopes. The reservoirs are widely distributed in stratified shape on plane, and presented multi-interval distributional patterns controlled by multi-stage karstification vertically with strong heterogeneity. Burial dolomitization is restricted by primary sedimentary facies, and can form extensive effective reservoirs in deep layers in stripe or stratified shape. Hydrothermally related reservoirs are generally distributed along discordogenic faults, forming effective reservoirs with beadlike distribution in vertical direction and band-fence like distribution on plane, which are not restricted by burial depth.
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  Nano-hydrocarbon and the accumulation in coexisting source and reservoir

  Zou Caineng; Yang Zhi; Tao Shizhen; Li Wei; Wu Songtao; Hou Lianhua; Zhu Rukai; Yuan Xuanjun; Wang Lan; Gao Xiaohui; Jia Jinhua; Guo Qiulin and Bai Bin

  , 2012, 39(1): 2002-0.

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  By comparison of the types, geological characteristics and exploration technologies of conventional and unconventional hydrocarbon, this paper proposes the concept of “nano-hydrocarbon” and indicates that “nano-hydrocarbon” is the development direction of oil and gas industry in the future. Nano-hydrocarbon refers to the research and production, by nano-technology, of oil and gas accumulated in the reservoir system of nano-sized pore-throats. It is mainly distributed in source rocks and the neighbouring tight reservoirs and includes shale oil, shale gas, coal-bed methane, tight sandstone oil & gas, tight limestone oil and so on, with nano-sized diameter of pore-throats in reservoirs. Oil, gas and water in nano-sized pore-throats exhibit poor percolation and phase separation, and are mainly driven by ultra-pressure, thus existing pervasively and continuously in the coexisting tight strata of source and reservoir. China’s petroliferous basins develop multiple series such as coexisting tight source and reservoir, carbonate fractures and cavities, volcanic fractures and cavities, and metamorphic rock fractures. Of them, the first type of series is located in the center or along the slopes of the basins, are accumulated extensively within or near sources and are dominant potential sources. With accumulations within coexisting source and reservoir in the Ordos Basin and Sichuan Basin as examples, the method of “two lines and one area” to prospect continuous-type hydrocarbon accumulation is proposed, i.e. the top and bottom boundaries of a set of coexisting source and reservoir and the boundaries of hydrocarbon accumulation as lines, and “sweet spot” distributing core area as main exploration target.
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  Integrated geophysical studies on the distribution of Quaternary biogenic gases in Qaidam Basin, NW China

  Yang Hui; Zhang Youyan; Ma Dade; Wen Baihong; Yu Shiyong; Xu Ziyuan and Qi Xiaoping

  , 2012, 39(1): 2003-0.

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  Quaternary biogenic gas fields in the Sanhu area of the Qaidam Basin are characterized by gentle structure, shallow burial, weak compaction, high porosity and large bulk thickness, which determine their unique geophysical anomalies, such as locally low gravity, micro-magnetic high frequency anomaly, seismic event push-down and attribute anomaly, etc. An integrated geophysical processing and interpretation scheme is put forward for shallow biogenic gas prediction in this area. Amplitude preserving is performed for 1:100000 gravity data and the processing results are correlated with the known gas distributions and the results of aeromagnetics, remote sensing and seismic hydrocarbon detection. Study shows that the residual gravity low anomaly has a good correlation with the gas field and is an important feature of the biogenic gas field, the amplitude of residual gravity low anomaly is directly proportional to the measure of gas reservoir. Based on the residual gravity low anomaly and other exploration data, the distribution of gas reservoirs in the Sanhu area is characterized by vertical overlapping, lateral zoning and local enrichment. Residual gravity anomaly, in combination with regional geologic data, reveals 3 favorable zones, 1 fairly favorable zone (low gas production zone), 5 possibly favorable zones and 4 favorable targets.
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  Three potential exploration areas of Southern Junggar Basin: Arguments from structural modeling

  Guan Shuwei; Chen Zhuxin and Fang Shihu

  , 2012, 39(1): 2004-0.

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  Three potential exploration fields of the southern Junggar Basin are proposed and discussed through seismic structural interpretation and three-dimensional geological modeling, in which the quantitative structural analysis techniques are used. The first field is Tertiary imbricate wedges in the core of the second anticlinal belt. These small-scale wedges contribute to different properties of oil, gas and water in different part of the same anticline. The second field is the deep Mesozoic structures composed of the fault-bend folds in the Jurassic-Cretaceous, which are different in sequences and levels from the overlying Tertiary wedges. The third field is the lateral transfer structures mainly in the second anticlinal belt, which are formed by transfer action between adjacent anticlines. Identification of the above three structural types must be based on pertinent seismic deployment and imagery processing. For the exploration of deep structures, a three-dimensional medium model, in which shear module, Lame’s constants and density are specified to truly represent mechanical properties of rock units, must be constructed firstly to calculate the restoration strains within the model by use of volumetric restoration technique. These strain data can help to predict the fracture azimuth, density and intensity of deep reservoirs.
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  Sequence lithofacies paleogeography and reservoir prediction of the Maokou Formation in Sichuan Basin

  Hu Mingyi; Hu Zhonggui; Wei Guoqi; Yang Wei and Liu Mancang

  , 2012, 39(1): 2005-0.

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  Based on the multidisciplinary analysis of outcrops, core description and log data, two kinds of sequence boundary are identified including partially exposed unconformity surface and drowned unconformity surface. The Maokou Formation in the Sichuan Basin is divided into three third-order sequences, each lasted 3.3 Ma on average. Taking systems tract as the mapping unit, the authors systematically compose the lithofacies paleogeography map within the sequence framework, and describe the distribution features of paleogeography. The results indicate that the Sichuan Basin is dominated by shallow water carbonate open platform deposit during the Middle Permian Maokou stage, in which sedimentary facies such as shallow water open platform, deeper water open platform, platform margin bank and platform front slope are developed. Physical property analysis indicates that shallow calcsparite granular limestone has good reservoir capacity, especially after the reservoir rock is reworked by dolomitization and epigenetic karstification. Thus, dolomite reservoir, paleokarst reservoir and shallow bank reservoir make up the main reservoirs of the Maokou Formation. The study on reservoir distribution rule within the sequence framework indicates that HST reservoirs are well developed relatively, especially the shallow bank sedimentary regions of SQ2-HST in western-southwestern Sichuan Basin and the paleokarst development area of SQ3 are the most favorable.
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  Reservoir evaluation and fracture characterization of the metamorphic buried hill reservoir in Bohai Bay

  Tong Kaijun; Zhao Chunming; Lü Zuobin; Zhang Yingchun; Zheng Hao; Xu Sainan; Wang Jianli and Pan Lingli

  , 2012, 39(1): 2006-0.

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  With core observation, thin slice identification and imaging logging data, reservoir evaluation and fracture characterization are studied in the Archaean metamorphic buried hill reservoir in the JZ25-1S field in Bohai Bay. The reservoir is divided into three zones vertically: weathered crust, semi-weathered crust and base rock, belonging to three reservoir types of fracture-pore pattern, pore-fracture pattern and micro fracture-compact pattern. The fracture effectiveness is estimated using crude oil inclusions testing technology, the direction of regional geostress, and full wave train acoustic logging data. It is concluded that the reservoir in the semi-weathered crust is most developed and the reservoir of pore-fracture pattern is the main oil producing layer. The main trend of fractures is nearly parallel to the main fault trend in the buried hill. The inclined fractures of late opening-mode parallel to the current direction of maximum geostress are the most effective fractures. At last, in combination of imaging logging interpretation with actual production, the qualitative and semiquantitative reservoir classification criteria are proposed and the buried hill reservoir is divided into three levels of I, II and III.
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  Controlling factors of low pressure reservoirs in the Sulige Gasfield, Ordos Basin

  Xu Hao; Zhang Junfeng; Tang Dazhen; Li Ming; Zhang Wenzhong and Lin Wenji

  , 2012, 39(1): 2007-0.

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  Based on the study of low-pressure distribution characteristics, the main factors that control the formation of low-pressure reservoirs in the Sulige gas field are analyzed from several aspects, such as structural evolution, sedimentary characteristics and formation fluid features. It is suggested that the gas pool pressure is low and affected greatly by buried depth. Its roof and floor developed several layers of uncompacted mudstone, indicative of good property and pressure sealing conditions. The formation water also indicates favorable preservation conditions. The reservoir pressure of the Sulige gas field experienced 4 major evolutionary stages: the normal pressure stage of the late Triassic-early Jurassic, the pressure rising stage of the middle Jurassic-late Jurassic, the sustainable pressure increasing stage of the early Cretaceous, and the pressure decreasing stage of the late early-Cretaceous. The pore rebound and temperature decrease caused by intense tectonic uplift after the late period of early Cretaceous, caused the reservoir pressure of the Sulige gas field to reduce by 0.673 MPa and 23.08% of the original strata pressure, respectively. The low pressure of the Sulige gas field is related to sedimentary assemblage, tectonic evolution and hydrocarbon accumulation.
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  Shale gas generation and potential of the Lower Cambrian Qiongzhusi Formation in Southern Sichuan Basin, China

  Huang Jinliang; Zou Caineng; Li Jianzhong; Dong Dazhong; Wang Shejiao; Wang Shiqian and Cheng Keming

  , 2012, 39(1): 2008-0.

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  According to the latest drilling data, the geologic survey of surrounding outcrops and the laboratory test results of rock samples, this paper studies the regional distribution, geochemical and reservoir characteristics and gas concentration of organic-rich shales to reveal the shale gas generation and potential of the Lower Cambrian Qiongzhusi Formation of the Southern Sichuan Basin. The study area features high organic content (with TOC between 0.55% and 25.7%, average of more than 2%), great net shale thickness (of 60—300 m), high brittle mineral content (over 40%), abundant micro- and nanometer-sized pores and micro-fractures, and high gas content (0.27—6.02 m3/t, average of 1.90 m3/t), which is in favor of the generation and accumulation of shale gas. The Lower Cambrian Qiongzhusi Formation is one of the most favorable strata which has frequent gas show and industrialization breakthrough during drilling, and the Weiyuan and Xunyong-Junlian areas are two most realistic and favorable targets for shale gas exploration and development.
油气田开发
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  Inorganic gel coating in-depth fluid diverting agent

  Tang Xiaofen; Yang Limin; Liu Yuzhang; Li Zhiyan; Chang Zeliang; Li Yikun and Wei Falin

  , 2012, 39(1): 2009-0.

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  The inorganic gel coating diverting agent, which is non-toxic and environmentally friendly, is developed for in-depth water diversion to improve water flooding effect. After being injected into the formation, the agent reacts with the formation water and forms inorganic silicate gel with a density approximating to formation water. The gel suspends in water as a bulk or particulates, scales and forms inorganic gel coating on rock surface by way of adsorption. The dominant channels of deep formation water are narrowed, forming flowing resistance and diverting the subsequent fluid so as to improve water flooding effect. This agent features fast solution, temperature resistance, salt resistance, environmentally friendly, and long-acting. It has been used in different reservoirs with different temperatures and salinity conditions, such as the Lunnan Oilfield of the Tarim Basin, the Yuejin oil region of the Qaidam Basin, and the Dagang Oilfield for in-depth profile control tests. The field tests involve single well group and whole block, with success ratio up to 100%, average injection pressure of well group increasing by 2-3 MPa, and the effective rate of oil production increase and water-cut decrease of producers reaching more than 80%.
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  Dual-porosity saturation model of low-porosity and low- permeability clastic reservoirs

  Li Xia; Zhao Wenzhi; Zhou Cancan; Wang Tongshan and Li Chaoliu

  , 2012, 39(1): 2010-0.

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  Abundant non-Archie phenomena have been discovered in rock electrical property experiments of reservoirs with low-porosity and low-permeability, and the classical Archie model is not suitable for the oil saturation calculation in these reservoirs. Based on the pore structure characteristics of these reservoirs, a new dual-porosity saturation model considering the effect of pore structure is presented, namely, the total rock resistance is considered as the parallel resistance of free water resistance and micro-pore water resistance. Both the effects of large pores and micro-pores on rock electrical properties are considered in this model. The model is applied to rock samples to derive the theoretical litho-electric relations which are in good agreement with the experiment measurement. The applications to low-porosity and low-permeability reservoirs of different origins in the east and middle of China show that, compared to the Archie model, the new model considers the effects of rock lithology, physical property, pore structure and oiliness on electrical properties. Therefore, oil saturation resulted from the new model is in good accordance with the real regularity and petrophysical characteristics of reservoirs, and it is much closer to the real oil-bearing conditions.
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  3D geological modeling of fractured volcanic reservoir bodies in Block DX18 in Junggar Basin，NW China

  Wu Jian; Sun Yuanhui; Wang Bin; Wang Yongjun; Xu Lei and Dai Chunmeng

  , 2012, 39(1): 2011-0.

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  The DX18 reservoir is composed of four mutually superimposed volcanic bodies and is a pore-fracture dual-media igneous reservoir. The fractures inside the volcanic bodies are mainly structural fractures with continuous distribution in space, and the continuity of fracture development positions is poor both vertically and horizontally. For the preparation of reservoir development scheme and further improving production well pattern, the fracture development and distribution characteristics are studied by 3D geological modeling. In view of the complexity of spatial structure of volcanic bodies, a body-controlled structure modeling is applied to describe the entire 3D shape of volcanic bodies. By integrating seismic data and logging interpretation, the relationship between various seismic attributes and fracture development zone is analyzed. Based on the analysis result above, a seismic-constrain modeling method which integrates the well data and seismic data is applied to establish the 3D property model for volcanic bodies. The fracture porosity model is constrained by seismic porosity data volume created by neural network processing, and the fracture density model is constrained by seismic dip volume. The later drilling and production performance proved that the main fracture development zones inside the volcanic bodies are accurately predicted and described by the seismic-constrain geological model and the coincidence ratio reaches 93.8%.
石油工程
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  Multistage hydraulic jet acid fracturing technique for horizontal wells

  Li Gensheng; Sheng Mao; Tian Shouzeng; Huang Zhongwei; Li Yuanbin and Yuan Xuefang

  , 2012, 39(1): 2012-0.

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  Acid fracturing in deep carbonate reservoirs is challenged by deep well stimulation with high temperature (>120 ℃), high fracture pressure (>2.0 MPa/m), high flow friction, and strong reservoir heterogeneity. To meet these challenges, a new stimulation method, called the hydraulic jet acid fracturing technique, was developed. According to the mechanisms of hydraulic jet acid fracturing, the authors self-design the downhole injector and pipe columns used in multistage hydraulic jet acid fracturing and provide optimization standards for nozzle number and diameter combination, abrasive perforating parameter, and pumping program. The technique realizes multistage acid fracturing by hydraulic separation and features simple downhole tools, high temperature resistance (160 ℃), low cost and risk. In addition, hydraulic acid injection can extend effective acid corrosion distance nearby well and enhance the acidification effect. The optimal jet phasing is 60 degrees with spiral arrangement to lower formation fracture pressure. A relationship chart between optimal flow rate and wellhead pressure is established, which helps to increase flow rate as far as possible under wellhead assembly capacity and to determine nozzle diameter and number. Results from field tests show that this method can work at a maximum depth of 6 400.53 m, with a total acid volume of up to 618 m3. It is effective in creating acid fractures in ultra deep horizontal wells.
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  Envelopes for connected operation of the deepwater drilling riser

  Ju Shaodong; Chang Yuanjiang; Chen Guoming; Liu Xiuquan; Xu Liangbin and Wang Rongyao

  , 2012, 39(1): 2013-0.

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  The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling platform and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and slip joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible joint and reduce the drilling envelope rapidly. The non-drilling envelope and emergency disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded.
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  A downward signal processing method for rotary steerable drilling system based on signal similarity

  Tang Nan; Wang Yuelong; Huo Aiqing and Cheng Weibin

  , 2012, 39(1): 2014-0.

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  To identify downhole command signals accurately and efficiently with negative fluid pulse intervals in the rotary steerable drilling engineering and solve the complex operation and high error rate problems in the command identification and explanation process of downhole receivers, this paper presents a signal process method based on signal similarity principle. In this method, command instructions expressed by drilling fluid pulse width signal are obtained by comparing the self-correlation degree of sampling signal amplitudes at each interval, and the downhole sampling signals are compared interval by interval according to a fixed rule, and command identification is achieved by three steps, i.e. judgment for the start of signal, calculation for digital bits of the command, and assembling of command word. The recursive practical algorithms suitable for downhole processing are proposed. The results show that the method can simplify operation program and improve the reliability and ability of interference killing for the signal identification, and is especially good for overcoming the effects of peak and periodic interference on time counting and the effects of inertia of transmitting channel and low frequency noise on signal jump edge judging.
学术讨论
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  Analysis of condensate oil in comprehensive two-dimensional gas chromatography

  Wang Huitong; Zhang Shuichang; Weng Na; Li Wei; Qin Shengfei and Ma Wenling

  , 2012, 39(1): 2015-0.

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  Twenty-two condensate oil samples from the Sichuan Basin are analyzed by comprehensive two-dimensional gas chromatography (GC×GC). Light hydrocarbon components are separated completely without the influence of co-eluting peaks, and the fingerprint information of light fraction such as propane remains intact. Sixty-seven compounds are detected in the range of nC3-nC8 by using GC×GC, 13 more than the compounds recognized in the conventional gas chromatography (GC). These compounds are divided into 12 compound classes by GC×GC according to the structure. Coupled with flame ionization detector (FID), some compounds that can not be analyzed quantitatively by other methods are quantified, including isoalkane, alkyl cyclopentane, alkyl cyclohexane, other single cycloalkane, polycyclic alkane, adamantane, alkylbenzene and polycyclic aromatic hydrocarbon and so on. The quantitative analysis results of more than 180 main compounds and the 12 compound classes by GC×GC will offer more technical assistance for petroleum geochemical researches to get new parameters of maturity estimation and oil-source correlation of condensate oil.