低渗致密气藏压裂水平井产能分析与完井优化

基于压裂水平井产能影响因素较多,基于常规产能评价方法的单因素敏感性分析法不能对各因素的影响程度做出综合定量评价,在建立并求解考虑裂缝干扰、裂缝污染表皮系数、裂缝不同分布形式、裂缝与井筒有限导流的压裂水平井产能预测模型基础上,通过正交试验分析得到压裂水平井产能影响因素的主次顺序。研究结果表明:压裂水平井产能影响因素的主次顺序依次为地层渗透率、裂缝污染表皮系数、地层有效厚度、裂缝半长、裂缝条数、裂缝导流能力、水平段长度、井筒半径和裂缝分布形式,其中地层渗透率、裂缝污染表皮和有效厚度对产能的影响尤为显著,而井筒半径和裂缝分布形式对产能无明显影响。对于实际水平井,在储层渗透率、有效厚度和储层规模等因素均无法改变的条件下,应尽量降低作业对储层的伤害,并根据实际地质参数进一步优化裂缝参数,这对提高水平井产量和开发经济效益具有重要意义。     

特低-超低渗透油藏分段压裂水平井开采参数优化研究及应用

通过建立水平井分段压裂物理模拟实验进行衰竭式开采、不同注采方式及不同驱替压差的实验研究.结果表明:相同时间内,压裂水平井半缝长为150 m时压力递减快、流速最大,随着裂缝长度增加,压力加快降低;增大压裂规模,水平井衰竭式开采速度加快.在相同驱替压差下,压裂水平井作为采油井时压力梯度高,在此基础上优化水平井开采参数,分析裂缝方位、裂缝形态、裂缝条数、裂缝间距、裂缝导流能力、水平段长度、射孔位置等对水平井开发效果的影响规律,水平段与裂缝近似垂直时开发效果最佳,最佳井网为七点法直井注水平井采井网,适当降低中间裂缝的长度和中间注水井的注水量可以起到稳油控水的作用,间断型纺锤形布缝时补充能量效果最好,优化后的参数与生产实际较好的吻合,优化结果可靠,对特低渗透储层分段压裂水平井开发具有重要的理论和矿场实际意义.     

吉林油田低渗透凝析气藏水力压裂裂缝参数优化

为了高效开发吉林油田X低渗凝析气藏,在分析原始井流物PVT实验结果的基础上,首先利用Eclipse软件PVTi模块建立组分模型,然后利用目标区块实际数值模型,对水力压裂裂缝参数及井底压力进行单因素分析和正交优化。结果表明:水力压裂能提高凝析气井产能,日产气量提高7~9倍,日产油量提高3~5倍;增加裂缝长度比增加裂缝导流能力有效;目标气藏压裂井存在最优井底压力12 MPa;对于吉林油田X低渗凝析气藏,最优的压裂裂缝参数为裂缝半长280 m,裂缝导流能力22μm2·cm。     

致密油藏水平井体积压裂裂缝扩展及产能模拟

阐述了地质因素和工程因素对体积压裂裂缝形态的影响;利用数值模拟方法,模拟了不同储层条件下水平井体积压裂裂缝扩展情况,分析了不同裂缝参数下水平井产能变化规律。结果表明:1对于高水平主应力差且天然裂缝欠发育储层,增加射孔簇数有利于提高裂缝复杂性;对于低水平主应力差且天然裂缝较发育储层,适当减少射孔簇数有利于增强体积压裂效果。2水平井体积压裂后产能比常规压裂有大幅增加,改造体积越大、导流能力越高,则产能越大;当地层渗透率从0.1×10-3μm2降低至0.001×10-3μm2时,次裂缝对产能的贡献程度从近1/6增加至近1/3。3当储层渗透率大于0.01×10-3μm2时,较大的簇间距(30 m)能减弱缝间压力干扰,保持较高产能;当储层渗透率小于0.01×10-3μm2时,压力传播速度慢,压力干扰相对较弱,较小的簇间距(15 m)有利于获得较高产能。     

致密气藏压裂水平井产能影响因素分析

针对致密气藏水平井开发产能主控因素难以明确的问题，基于致密储层渗流理论，建立了考虑应力敏感因素的压裂水平井渗流模型，根据渗流模型分析了裂缝条数、裂缝长度、裂缝导流能力以及应力敏感等因素对水平井产能的影响。结果表明，压裂水平井单井产能随着裂缝条数增多、裂缝半长增大及导流能力增强而增大，随着应力敏感的增强而减小。通过定量比对，明确了各因素与压裂水平井产量的相关性为：裂缝数量>裂缝半长>应力敏感>导流能力。该项研究对水平井产能评价以及致密气藏水平井开发井网正确部署具有一定的指导意义。     

特低渗透油藏压裂水平井衰竭开采参数优选研究

为深入系统地研究压裂裂缝各参数对水平井开发效果的影响,应用特低渗透油藏非线性渗流数值模拟软件,以长庆油田某区块为研究对象,给出特定区块的最优裂缝参数,并分析各裂缝参数的敏感性。结果表明,在特定储集层渗透率条件下,压裂水平井具有最优的水平井长度、裂缝形态、裂缝条数、裂缝长度、裂缝导流能力;通过不同渗透率级别和水平井长度下的裂缝参数优选可知,对于压裂水平井衰竭开采效果最为敏感的参数是裂缝条数,其次是裂缝长度,裂缝导流能力最为不敏感。     

大厚层致密砂砾岩油藏直井多段压裂开发研究

针对纵向厚度比较大的低渗砂砾岩油藏,须选用直井压裂多段纵向裂缝的开发方式,本文采用数值模拟的方法展开研究.首先对比了分别采用分支水平井和多段压裂直井两种开发方式在厚层低渗油藏里的效果;然后分析了裂缝导流能力、供油面积、地层渗透率等产能影响因素,做出裂缝长度、Cf/Km(裂缝导流能力与地层渗透率之比)与累产的图版以用于压裂设计优化,同时研究了韵律与极差对开发的影响;最后研究了裂缝长度、高度、间距分布等布缝原则,以指导实际压裂方案。     

大厚层致密砂砾岩油藏直井多段压裂开发

针对纵向厚度比较大的低渗砂砾岩油藏,需选用直井压裂多段纵向裂缝的开发方式,采用数值模拟的方法展开研究.首先对比了分别采用分支水平井和多段压裂直井两种开发方式在厚层低渗油藏里的效果;然后分析了裂缝导流能力、供油面积、地层渗透率等产能影响因素,作出裂缝长度、C_f/K_m(裂缝导流能力与地层渗透率之比)与累产的图版以用于压裂设计优化,同时研究了韵律与极差对开发的影响;最后研究了裂缝长度、高度、间距分布等布缝原则,以指导实际压裂方案。     

苏里格东区致密气藏压裂水平井产能影响因素及其优化设计

对苏里格东区某实际致密气藏进行了压裂水平井产能影响因素分析,得到主控因素,并据此完成不同储层条件下压裂水平井参数设计的优化图版.结果表明:地层渗透率越低、各向异性越强,则水平井段和裂缝的最优长度越大,最优压裂裂缝间距越小,且各影响因素对增产效果影响具有相关性.     

气藏压裂水平井裂缝参数优化分析

裂缝参数是影响压裂水平井产能的主要因素,为了优化合理的裂缝参数,建立水平井及裂缝耦合的数学模型,该模型综合考虑压裂水平井长度、井筒摩擦阻力、裂缝条数、裂缝长度、裂缝导流能力、裂缝间距等影响因素,应用Green函数和Newman乘积原理,给出压裂水平井不稳定渗流下的产能求解方法。研究表明:压裂水平井产能随着裂缝导流能力的增加而增大,但是当导流能力增加到一定程度后,产能增加的幅度开始逐渐变小。对于压裂水平井存在最优的裂缝导流能力;对于裂缝条数已知,压裂水平井长度存在一个最优值;对于水平井长度已知,则存在最优的裂缝条数;裂缝条数与水平井长度之间存在最优的匹配关系。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.