库车坳陷深层断裂控藏作用及其成因机制

发布时间：2018-07-18 16:42

【摘要】：作为非常规油气资源的重要组成部分,沉积盆地深层致密砂岩气蕴含巨大资源潜力,是未来油气勘探的重要领域。近年来的勘探实践表明,中国典型致密砂岩气藏发育的构造背景相对复杂,特别是多期次构造运动形成的断裂对致密砂岩气成藏具有重要的控制作用,并导致致密砂岩气藏的分布规律复杂多变。但传统的致密砂岩气成藏理论既无法解释复杂地质背景下致密砂岩气藏的成藏机制,也无法定义致密砂岩气藏的富集分布规律。因此,本文首先在典型气藏解剖的基础上分析了断裂对致密砂岩气富集成藏的促进作用,并揭示了断裂促进致密砂岩成藏的主控因素和成因机制,建立了断裂促进深层致密砂岩气成藏的评价方法。在此基础上,通过典型气藏解剖,分析断裂对致密砂岩气藏的破坏作用,重点分析断裂对致密砂岩气藏的破坏范围及其主控因素,并揭示断裂对致密砂岩气藏的破坏机制,建立评价断裂破坏致密砂岩气藏范围的评价方法。最后,利用评价模型预测迪北地区断裂促进致密砂岩气成藏与富集的有利区和断裂导致致密砂岩气藏贫化与破坏的不利区。研究表明,断裂促进致密砂岩气富集成藏的三种关键地质条件为:断裂活动强度、断裂与盖层的空间配置关系以及致密储层距断面距离。当断裂活动速率小于某一临界值且存在有效盖层的情况下,早期发育断裂有利于天然气在致密储层中聚集成藏,且越靠近断裂带的位置,天然气富集程度越高,越容易形成“甜点”。断裂在致密储层中形成双重介质,减小了天然气的充注阻力(毛细管压力),改善了致密储层的渗流条件;断裂形成的二级充注带使得天然气由气源岩与致密储层充注效率较低的面状充注转变为面状充注和沿断裂带的高效充注的复合充注方式,浮力和气体膨胀力共同驱动天然气在断裂带内的充注。断裂促进致密砂岩气成藏富集的评价模型显示,断裂活动强度、断裂与盖层的配置关系、距断裂距离的耦合关系决定了致密砂岩储层中天然气的富集程度。该评价模型可以定量预测断裂作用下致密砂岩藏的含气饱和度,并由此预测天然气富集区和“甜点”。断裂对致密砂岩气藏的破坏实际上是改变了致密砂岩气的浮力作用下限,由于断裂诱导的裂缝带孔喉半径较大、渗透率较高,浮力作用下限的力平衡条件不再满足,致密砂岩气藏发生贫化。断裂断距控制了断裂破坏浮力作用下限的范围,断距越大,断裂对浮力作用下限的破坏范围越宽。由断裂带核部至断裂带与围岩渗透率相当的宽度即为断裂破坏浮力作用下限的宽度。迪北地区致密砂岩气有利富集区主要分布在F1断裂(依奇克里克断裂)和F3断裂之间的斜坡位置、F5断裂的东部以及F7断裂(迪那北断裂)等部分地区。由于晚期活动速率较大,且无有效盖层保护,F1和F2断裂对已经聚集成藏的致密砂岩气藏起到破坏作用。以F1断裂为例,F1断裂在依深4井附近对致密砂岩气藏的破坏范围大约为1200m左右。经钻探实践证实,该预测结果与实际勘探结果基本吻合,说明评价模型可以客观地评价断裂对深层致密砂岩气的控制作用。
[Abstract]:As an important component of unconventional oil and gas resources, the deep and dense sandstone gas in the sedimentary basin contains great resource potential and is an important field of future oil and gas exploration. In recent years, the exploration practice shows that the tectonic setting of the typical tight sandstone gas reservoirs in China is relatively complex, especially in the dense sandstone formed by multiple stages of tectonic movement. Gas reservoir plays an important role in controlling the distribution of tight sandstone gas reservoirs, but the traditional dense Sawa Kesunghide theory can not explain the formation mechanism of tight sandstone gas reservoir under complex geological background, and can not define the distribution law of the dense sandstone gas reservoir. On the basis of the analysis, the effect of fracture on gas accumulation in tight sandstone is analyzed, and the main controlling factors and genetic mechanism of fracture promoting the formation of tight sandstone are revealed, and the evaluation method of fracture promoting deep and dense Sawa Kesunghide is established. On this basis, the failure effect of fracture to tight sandstone gas reservoir is analyzed by typical gas reservoir anatomy. The damage range of fracture to tight sandstone gas reservoir and its main controlling factors are emphatically analyzed, and the failure mechanism of fracture to tight sandstone gas reservoir is revealed, and the evaluation method for evaluating the scope of the tight sandstone gas reservoir is established. Finally, the evaluation model is used to predict the favorable areas and the fracture conductance of the gas accumulation and enrichment of the dense sandstone gas in the north of Debei area. The study shows that the three key geological conditions for the accumulation of tight sandstone gas accumulation are the strength of fracture activity, the spatial distribution of fracture and the cover layer and the distance from the dense reservoir to the cross section. When the rate of fracture activity is less than a certain critical value and the effective cap is present, The early development fracture is beneficial to the accumulation of natural gas in the dense reservoir, and the closer to the position of the fault zone, the higher the concentration of natural gas, the more easy to form a "dessert". The fracture is formed in the dense reservoir to form a double medium, which reduces the filling resistance of natural gas (capillary pressure) and improves the percolation condition of the tight reservoir; fracture formation is formed. The two grade filling belt makes the natural gas from the gas source rock and the tight reservoir filling efficiency lower in the surface filling to the surface filling and the high efficiency filling and filling way along the fracture zone. The buoyancy and the gas expansion force jointly drive the natural gas to fill in the fracture zone. The relationship between the strength of fracture activity, the distribution of fracture and the cover layer, the coupling relationship between the distance from the fault and the fracture distance determines the concentration of natural gas in the tight sandstone reservoir. The evaluation model can predict the gas saturation of the dense Sawa Hide under the fracture, and then predict the natural gas enrichment area and the "dessert". In fact, the lower limit of the buoyancy of tight sandstone gas is changed, because the fracture induced fracture zone has larger pore throat radius, high permeability, and the pressure balance condition of the lower buoyancy limit is no longer satisfied, and the tight sandstone gas reservoir is poor. The fracture break distance controls the range of the lower limit of the fault buoyancy, the greater the break distance, the fracture is to buoyancy. The width of the fracture zone from the core of the fault zone to the fracture zone is the width of the lower limit of the fracture buoyancy. The favorable enrichment area of the dense sandstone gas in the north of Di is mainly distributed in the oblique slope position between the F1 fault (Yiqi Crick fault) and the F3 fault, the east of the F5 fracture and the F7 fracture (Dina). In some parts of the North Fault), the F1 and F2 faults have played a destructive role in the tight sandstone gas reservoirs that have been accumulations because of the higher rate of late activity and no effective cover protection. In the case of F1 fracture, the damage range of the F1 fracture to the tight sandstone gas reservoir near the well 4 well is about 1200m. The actual exploration results are basically consistent, indicating that the evaluation model can objectively evaluate the control effect of faults on deep tight sandstone gas.
【学位授予单位】：中国石油大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P618.13

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