【作者】 胡杰；

【导师】 喻高明；

【作者基本信息】 长江大学 ， 油气田开发工程， 2015， 硕士

【摘要】 国内外低渗透油田的开发已有近百年的历史,其中美国早在1871年发现并开发了世界著名的勃莱德福低渗透砂岩大油田(平均渗透率7.510×10-3μm2、平均孔隙度15%)。在我国低渗透油田开发也有着悠久的历史,1907年9月10日,我国陆上钻成第一口油井—延长油田1号井,其产层就是举世闻名的特低渗透层—三叠系延长统油层。从国内外有关报道情况来看,对低渗透油田基本的地质特征和开发特征有如下认识：(1)储层物性差,渗透率低。由于颗粒细,分选差,胶结物含量高,经压实和后生成岩作用使储层变得十分致密,渗透率一般小于100×10-31.μm2,少数低于1.0×10-3μm2：(2)储层孔隙度一般偏低,变化幅度大。大部分在7%～20%分布,个别高达25%(美国巴罗岛油田),多数低渗透油田的有效厚度有限,所以储量丰度普遍偏低；(3)原始含水饱和度较高,原油物性较好。一般含水饱和度在30%—40%,个别高达60%(美国的东堪顿油田),原油密度多数小于0.85,地层原油粘度多数小于3 mPa.S。这就决定了低渗透油田虽能注水,但水淹速度偏快；特低渗透油藏的显著特征是储层渗透率远低于中高渗透油藏、渗流存在启动压力梯度、部分微裂缝发育,因此,特低渗透油藏分层注水标准有其特殊性：(1)特低渗透油藏如长庆虎狼卯长6油藏裂缝较发育,对注水开发效果影响较大,因此对隔层厚度及稳定性要求更高；(2)层段内小层数根据层段内渗透率变异系数、突进系数进行控制,均质性越差,小层数越少；(3)特低渗透油藏渗透率特低、存在启动压力梯度,水井一般需要压裂投注,需要更高的注水压力才可正常注水；历年测试吸水强的层尽量单卡单注;(4)低渗透油藏注水形成优势通道后,目前无有效调剖堵水技术,因此应对注水量进行控制,防止油藏在低采出程度期油井大面积水淹；长庆超低渗透油藏自规模开发以来,受储层吸水差异影响,逐步表现出水驱动用程度低、地层压力保持水平低及递减大等问题。近年来,为改善吸水状况,提高水驱动用程度,使纵向分层注水分布均匀,进行分层注水。目前超低渗油藏主要采用两层分注,为满足精细注水要求,还需开展多层分注。本文在把握油水流动特征的基础上,对油藏注采系统进行了等效表征,建立了能够综合考虑压缩性和关停井情况的井间动态连通性模型。在此之上基于贝叶斯理论和投影梯度法,建立了连通性模型整体约束优化方法,为动态分析、裂缝建模提供了新的方法和数据。创新建立了分层注水标准。在非均质性影响水驱效率分析基础上,确定分层注水后,综合运用开发动态、动态监测及数值模拟研究方法,建立油藏精细分层注水技术标准,即层间渗透率级差小于3；隔层厚度≥1m,为精细分层注水方案的制定提供依据。运用油藏工程、开发动态数理统计、经验法及数值模拟方法相结合,制定出地层压力、井底流压及注水强度等精细注水政策。油藏合理地层压力12.1MPa;合理井底流压6.0—7.5MPa模拟区合理注采比为1.1,合理采液速度1.7%,预测方案采出程度12.81%(模拟十年),累产油26.65万方。更多还原

【Abstract】 Development of low permeability oil fields for nearly a hundred years of history at home and abroad, early in 1871, the United States discovered and developed the world-famous Grand Bly Telford low permeability sandstone oil (average permeability 7.510.05 × 10-3μm2, the average porosity of 15%). In our country the development of low permeability reservoirs also has a long history, September 10,1907, China’s first oil well drilled on land - Yanchang Oilfield No.1 Well, its production level is world-famous ultra-low permeability layer - Triassic Yanchang oil. From the reports at home and abroad, an basic understanding of geological features and the development characteristics was got toward the low permeability reservoirs:(1)poor reservoir properties, low permeability. As the fine particles, poor sorting, high cement content, generated by the compaction and the role of reservoir rock becomes very dense, permeability is generally less than 100 × 10-3 μm2, minority of which is less than 1.0 × 10-3 μm2;(2)Reservoir porosity is generally low and varies much. Most of which ranged from 7% to 20%, the individual up to 25% (U.S. Barrow Island oil field), Majority of low permeability oilfield has limited effective thickness, so reserve abundance is generally low;(3) High initial water saturation and better crude oil properties. Average water saturation of 30% to 40%,some of which up to 60% (American worthy of Dayton East oil), the majority of oil density is less than 0.85, oil viscosity of less than 3 mPa. S. This determines the reservoirs with low permeability got easily flooding.Ultra-low permeability reservoir is characterized by a significant reservoir permeability is much lower than in high-permeability reservoirs, percolation threshold pressure gradient, some micro-fractures, therefore, ultra-low permeability reservoir stratified water standard has its particularity:(1) ultra-low permeability reservoirs such as tigers Mao Changqing Chang 6 reservoir fracture is developed, a greater impact on waterflooding effect, so the barrier thickness and stability requirements are higher;(2) layer based on a small number of layers within layers segment penetration coefficient of variation coefficient onrush control, heterogeneity worse, fewer small number of layers;(3) ultra-low permeability reservoir permeability special low starting pressure gradient wells generally require fracturing betting, you need to be a higher injection pressure normal water; over the years a strong layer of absorbent try to test a single card single note;(4) the formation of the advantages of low permeability reservoir water channel is currently no effective EOR technology, so deal with water injection to control and prevent the reservoir at a low level of recovery of oil flooded a large area;since the scale development of ultra-low permeability reservoir of Changqing oilfield, as the influence of different water absorption between layers, gradually driving the performance of the low level of water, maintain a low level of formation pressure and production declining such problems. In recent years, in order to improve the poor water absorbing conditions, improve water drive extent that the water evenly distributed vertical stratification, stratified water. Currently the main use of ultra-low permeability reservoirs two dispensing, in order to meet the requirements of fine water, the need to carry out multi- layered water flooding.In this paper, seize the oil-water flow characteristics, based on the injection system for reservoir characterization equivalent, capable of considering the establishment of an inter-compression and shut down wells wells dynamic situation connectivity model. On top of this based on Bayesian theory and the gradient projection method, a model of the overall connectivity constrained optimization method, and provides a new approach to dynamic data analysis and fracture modeling. Innovation and the establishment of a stratified water standards. After the impact of heterogeneity on the basis of waterflood efficiency analysis to determine the stratified injection, integrated use to develop dynamic, dynamic monitoring and numerical simulation methods to establish technical standards for fine reservoir water stratification, namely inter-layer permeability ratio of less than 3 ; barrier thickness ≥1m, provide the basis for the development of fine stratified water injection program.By reservoir engineering analysis and the development of dynamic mathematical statistics, the empirical method and numerical simulation methods are combined to develop a rational formation pressure, bottomhole pressure and water injection intensity, and other fine water policy. Reasonable reservoir formation pressure 12.1MPa; reasonable bottomhole pressure of 6.0-7.5MPa; reasonable injection-productio ratio of 1.1, a reasonable liquid-production rate of 1.7%, predicted the recovery of 12.81% recovery program (simulation ten years), cumulative oil production 26.65.更多还原