Practices at home and abroad have proved that carbon dioxide flooding is one of the most successful technologies to enhance oil recovery.Due to the high flowability of gas,gas channeling is an important problem in the process of gas injection.The technology of single sand body anatomy is a very effective method to charac-terize reservoir heterogeneity.In this paper,based on the dense well data and guided by the high resolution se-quence stratigraphy theory,using hierarchy interface analysis technology,we studied the interlayer distribution patterns and sand bodies stacked patterns to anatomize single genetic sand body size distribution and morphology in three-dimensional space.Meanwhile,we established physical properties standards of high permeability belt to describe its distribution zone and to predict gas channeling direction and magnitude.In addition,on the base of single sand body anatomy and gas channeling evaluation,we built a set of technology process which was applied to single sand body anatomy in the process of gas flooding.This technology can scientifically solve the problem of gas channeling,and provide reference for reservoir heterogeneity research methods.

松辽盆地南部长岭断陷登娄库组致密砂岩地层陆续发现了新的天然气区带,显示出巨大的勘探开发前景.利用大量岩心描述及分析化验资料,对登娄库组致密砂岩储层发育的控制因素进行了研究.对比研究认为,埋藏史是控制地区间储层物性差异的主要因素;而在埋藏史相近的地区,沉积微相是控制储层发育的主要因素.沉积分异过程造成不同微相储层岩石学性质的分异,而不同岩石相在成岩作用发生不同孔隙演化过程,其机制为:粒度粗、泥质少的砂岩,在压实过程中趋向于保留更多的原生孔隙,为溶蚀过程提供流体通道,导致溶蚀孔更发育,物性最好;含泥质砂岩中,泥质杂基在压实过程中强烈形变,充填孔喉,降低了物性,特别是降低了渗透率;与泥岩接触的砂岩,极易发生早期碳酸盐胶结,大幅降低了储层孔隙度.根据以上分析认为,心滩中下部及辫状河道中部砂岩最利于形成优质储层.通过对孔隙演化过程的模拟,定量印证了以上观点.

据AAPG的资料,全球已发现的370个大气田集中分布在西西伯利亚盆地、波斯湾盆地、扎格罗斯盆地、卡拉库姆盆地、墨西哥湾盆地、卡那封盆地以及东西伯利亚盆地,分布在上述盆地的大型气藏占总数量的45％,其储量占到大气田储量的68.3％.在分析所有大型气藏资料的基础上,研究了大型气藏的数量、储量、地区、地层、圈闭类型、深度、发现时间等特征.依据“实用性、针对性和科学性”分类原则,围绕岩性、厚度、规模、物性、压力、流体等因素将大型气藏划分为5种类型:①厚层整装高渗透砂岩气藏,规模大、储层厚、物性好、或存在边底水;②低渗透砂岩气藏,规模大、物性差、一般不存在边底水;③边底水裂缝型碳酸盐岩气藏,规模大、裂缝发育、存在边底水;④高温、高压、高含硫“三高”气藏;⑤凝析气藏,压力温度异常、相态复杂、常常发生反凝析现象.厘清大型气藏的分布特征为我国天然气藏的勘探指明了方向,总结出的不同类型大型气藏的开发特征也为相同类型气藏的经济、高效、安全开发提供了宝贵的经验.

Based on large amounts of data of lithological characters,physical property, pore structure and thin section, we paraphrased controlling factors of the reservoir development in combination with sedimentary elements and diagenesis. The results indicate that Denglouku Formation sandstone belongs to braided delta plain subfacies in Changling gas field, composed of feldspathic lithic sandstone, the reservoir space consists in the intergranular dis- solved pores, associated with low porosity and permeability. Rock source is the basis of sand bodies, the physical properties of quartz sandstone are better than that of lithic quartz sandstone and lithic sandstone. Both sedimentary evolution and position of secondary pores control the distributive intervals of effective reservoir. The plane hetero- geneity is constrained by sedimentary mierofacies and diagenetic facies. Strong compaction and cementation are the dominant factor to create the low permeability reservoirs,in contrast that dissolved secondary pores are in favor of relatively high permeability zones so as to make the low permeability reservoir become better.

In order to understand the control action of sedimentary facies on reservoirs in Changling gas field, a comprehensive investigation has been conducted in respects of depositional setting, core description, and grain size analysis. It is determined that the Denglouku formation in Changling gas field belongs to delta plain facies in shallow lake environment, mainly including four microfacies, which are branch channel, interchannel, crevasse splay and natural levee. The characteristics and distribution of each microfacies are determined by combining with logging and core analysis data, and the control action of sedimentary microfacies on effective reservoirs is understood. The branch channel contributed the most to effective reservoir development, crevasse splay and natural levee were the next, and no effective reservoir had developed in interchannel microfacies.

The key to develop tight gas reservoir was to find out the relative-high permeability reservoirs.By taking Sulige Gas Field for example,one of it was investigated in this study and the information from reservoir lithology study,well log and seismic data were combined to make an comprehensive analysis of relative-high permeability reservoir,including microscopic features and response characteristics of well logs and seismic tests.The combination of secondary sedimentary-facies-restitution,well log identifying induced porosity,sand superposition law research,AVO analysis and facies-controlled-stochastic modeling was suggested to predict relative-high permeability sandbodies.As the outcome of this research,the distribution law of relative-high permeability reservoir derived from braid rivers may provide a sound support for effective development of Sulige Gas Field.It could also be introduced to guide the development of similar gas fields.

Denglouku unit is the primary formation of Changling Gas Field loacted in the south of Songliao basin.Its deep cover depth and strong lithogeny play an important role in its development of porosity and porosity structure.It's believed that well developped secondary porosity is the key factor which ever controlled the accumulation of natural gas.Laboratory tests and Analysis,such as thin section analysis,were applied in the research to find out the characteristic of diagenesis and porous structure.Based on this result,its secondary porosity development area was clarified,which may be used to guide the field's futher development.

Sulige gas field is characterized by low gas richness, extraordinarily low permeability, and significant reservoir heterogeneity. Formation of the gas field was deposited in a braided-river environment. Most of its net effective sandbodies, featured by small size and poor continuousness and connectivity, are dispersively distributed in the tight sandstones and mudstones in shapes of isolated spots or narrow strips. In order to get an optimum development strategy for the gas field, numerical simulation of a trial block has been performed. Simulation results show that well pattern of 1200×600m is the best for the gas field. "Sequential" development of infill has the merits of delaying investments by delaying of drilling wells & surface facilities and improved economics outcomes. Basic well pattern completed in period of initial capacity construction benefits for learning more geologic characteristics and increasing success ratio of development well. In later period of the development, blocks which still have production potential can be down spaced again to improve gas recovery.

SMA hard-gel sealing agent is made up of host-compound,cross-linking agent and delay agent.The gelation time of the hard-gel sealing agent can be controlled by adjusting the dose of the delay agent.The performance experiments of the gel are made with man-made cores,and the results show that the gelation time is 72 h at 50℃;The sealing ratio of the gel sealing agent is greater than 99.9%,and it is not also lower than 99.8% after the water of 50 PV is injected;The breakthrough pressure gradient is not lower than 3.4 MPa/m usually.The visual fracture-sealing experiment is made with glass sandpack column,and it is obviously observed that SMA hard-gel can effectively sealing the fractures,the sequential injected water changes its direction,and its swept area evidently increases.In the sealing experiments with long man-made cores, a great amount of SMA solution is injected,and fractures can be blocked for a long time,which improves the utilization efficiency of the sequential injected water and oil recovery factor can been enhanced by 31.76% based on the recovery factor of initial water flooding.