【作者】 杨晶；

【导师】 宋考平；

【作者基本信息】 东北石油大学 ， 油气田开发工程， 2011， 博士

【摘要】 我国低渗透油田储量资源丰富,但是受目前技术条件的限制,其采收率一般只能达到20%左右。为提高低渗透油田采收率和产量,迫切需要研究新的驱油剂和驱油方式。国内外大量研究结果表明,CO2驱可以较大幅度地提高油气采收率,而且没有污染,有利于环境保护,因此采用CO2驱油开发低渗透油田具有广阔的前景。为准确预测不同CO2注入方案下动态指标的变化规律,并确定最优注入方案,需要进行数值模拟研究。但现有的商业化CO2驱数值模拟软件都是基于达西定律开发的,没有考虑启动压力梯度的影响,不能够完整地反映低渗透油藏CO2驱油的全过程,有必要建立考虑非达西渗流规律的CO2驱数值模拟模型。本文首先开展了CO2驱油室内实验,测定了CO2驱油的最小混相压力和启动压力梯度,然后通过研究低渗透油藏CO2驱油机理以及流体的非达西渗流规律,在现有组分模型的基础上,考虑油、气、水三相启动压力梯度,建立了低渗透油藏CO2驱油三维三相多组分非达西渗流模型,采用有限差分方法和IMPES方法进行了数值求解,同时开发出一套适用于低渗透油藏CO2驱油的数值模拟软件,并通过室内驱油实验验证了该模型以及自主开发软件的正确性和适用性。根据树101区块和树16区块的地质特征及开发现状,应用Petrel地质建模软件分别建立了这两个区块的相控地质模型,然后利用自主开发的数值模拟软件对树101区块进行了CO2驱油数值模拟研究,对树16区块进行了CO2吞吐数值模拟研究。树101区块CO2驱油数值模拟研究结果表明,该区块以线性注气方式为最优井网；结合经济效益评价结果,连续注入、单段塞注入和水气交替注入三种CO2注入方式中水气交替注入为最优注入方式,其最优注入参数为：气水比为1：1,段塞大小为0.03PV,日注入量为200m3(即液态CO2年注入量为0.050PV),CO2总注入量为0.3PV,后续水驱年注入量为0.12PV。该注入方式20年末采出程度为25.15%,比基础方案提高6.15%。树16区块的CO2吞吐数值模拟研究结果表明,以换油率和增油量作为评价指标,优选11Y67-611井最佳吞吐参数为：日注入量80m3,周期注入量100m3,焖井时间30天,吞吐2个周期,增油量和换油率分别为101.31m3和1.01m3.m-3；优选1Y69-56井最佳吞吐参数为：日注入量60m3,周期注入量135m3,焖井时间30天,吞吐3个周期,增油量和换油率分别为154.38m3和1.14m3.m-3。上述研究结果表明,基于C02驱油非达西渗流理论模型的数值模拟技术能够准确地模拟榆树林油田CO2驱油过程,适用于榆树林油田注气开发方案设计,对其他同类型油田应用CO2驱提高原油采收率具有重要的指导意义。更多还原

【Abstract】 There are rich resources of low permeability oilfields in China, whose recovery can only reach 20% commonly limited by the current technical conditions. In order to improve oil recovery and production of the low permeability oilfield, new displacement agents and methods should be urgently investigated. Domestic and foreign research results indicate that CO2 flooding can greatly improve oil recovery, and has no pollution favorable to environment protection, so using CO2 flooding to develop the low permeability oilfield has wide prospect.In order to accurately predict the variations in dynamic indexes of different CO2 injection schemes and determine the optimal scheme, numerical simulation research should be conducted. But the existing commercial CO2 flooding numerical simulation software was developed based on the Darcy flow without considering the influence of actuating pressure gradient, which could not fully reflect the whole CO2 displacement process of low permeability reservoirs, and therefore it is necessary to establish a CO2 flooding numerical simulation model considering non-Darcy flow pattern.This paper firstly conducted CO2 flooding lab experiments to measure minimal miscibility pressure and actuating pressure gradient, and then on the basis of the studies on CO2 flooding mechanisms, the non-Darcy flow pattern of low permeability reservoirs and the existing component model, a three-dimensional three-phase multi-composition percolation mathematical model suitable for CO2 flooding of the low permeability reservoirs has been established, which considered the actuating pressure gradient of oil, gas and water. After that, numerical solution was brought out by finite-difference method and IMPES method, and a set of CO2 flooding numerical simulation software suitable for low permeability reservoirs was then developed. Finally correctness and applicability of the model and developed software both were verified by core experiment.According to geological features and present development situation of Shu101 block and Shu16 blcok, facies-controlled geological models of the two blcoks were established by Petrel geological modeling software. And then using the self-developed numarical simulation software, this paper conducted numerical simulation research on CO2 flooding of Shu101 block and CO2 huff and puff of Shu 16 block.The results of numerical simulation research on CO2 flooding of Shu101 block showed that linear gas injection mode between the two designed well pattern adjustment schemes. Combained with the economic benefit evaluation results, water alternating gas injection mode among the three CO2 injection modes of continuous gas injection, single slug injection and water alternating gas injection has been confirmed to be the best, whose optimum parameters were that 0.3PV of CO2 injection quantity,0.03PV of slug size,1-1 of gas-water ratio,200m3 of liquid CO2 injection rate (i.e.0.050PV of liquid CO2 annual injection rate), and 0.12PV of subsequent water annual injection rate. The recovery degree of this scheme could reach 25.15 percent in 20 years, which could increase 6.15 percent than the foundation scheme.The results of numerical simulation research on CO2 huff and puff of Shu 16 block showed that taking oil-draining rate and oil increment as evaluation indexes, the optimum huff and puff parameters of well 11Y67-611 were that80 m3/d of injection rate,100 m3 of cycle injection volume,30 days of soak time and two cycle of puff and huff, while the oil increment and the oil-draining rate were separately 101.31 m3 and 1.01 m3-m-3. The optimum huff and puff parameters of well 11Y69-56 were that 60 m3/d of injection rate,135 m3 of cycle injection volume,30 days of soak time and three cycle of puff and huff, while the oil increment and the oil-draining rate were separately 154.38 m3 and 1.14 m3·m-3.The above reaserch results showed that the numerical simulaton technique based on the non-Darcy flow theorical model of CO2 flooding could simulate CO2 displacement process in Yushulin oilfield accurately and was suitable for designing the development scheme of Yushulin oilfield, which has important guiding significance for other same type oilfields to improve oil recovery by CO2 flooding.更多还原