考虑水侵影响的多尺度缝洞型油藏产量不稳定分析理论研究

Fractured-caved carbonate reservoir is the main reservoir type of carbonate reservoirs in China. It is really important with an OOIP over 2.6 billion tons and oil rate over 11 million tons per year. Dissolved vugs, fractures and caves are developed in fractured-caved reservoir, which result in the complicated reservoir pore structures. The oil-water-contact of fractured-caved carbonate reservoir is very complicated, which have different oil-water contacts for different reservoir units. The success ratio of new well drilling is much lower than that of other reservoirs. The performance is also much poor. This is attributed to the misunderstanding of reservoir volumes and oil-water-contacts. The dynamic characterization method based on Darcy fluid flow theory is not accurate enough with an observable error, and also unable to distinguish the volume of oil and water in the reservoir, which generate the wrong value of OOIP and aquifer size. The study will firstly build the mathematic models of rate transient analysis with fluid flow coupled by Darcy flow and free fluid flow and aquifer influx for different simplified multi-scaled fractured-caved reservoirs. And the equations of dimensionless parameters for the boundary dominated fluid flow will be characterized for the unit slope generation. The models will be solved by analytical method considering fluid flow coupled by Darcy flow and free fluid flow and aquifer influx. Then the mathematic models of rate transient analysis characterized by two-phase flow coupled by Darcy flow and free fluid flow for the fractured-caved network will be established, and the interface of Darcy flow and free fluid flow also oil phase and water phase should be deeply studied and solved. Then fast solutions for the models will be studied through numerical methods and reservoir parameters will be calculated. Experiment results and the forward modeling method by reservoir simulation will be used to check the reliability of the theory and methodology with the programming evaluation software. Finally, the results will be applied in Tarim Oilfield, and the OOIP and aquifer size would be quantitatively calculated respectively for each reservoir through the proposed theory, also the oil-water contact could be calculated for each development reservoir unit, which will be used for the deployment of new wells and the stimulation of existing wells.

我国碳酸盐岩油藏以缝洞型为主，产量规模达1100万吨/年，是一种重要的油藏类型。缝洞型油藏储集空间多样，不同尺度的孔、缝及洞发育，各储集体普遍有水体但不具有统一油水界面。该类油藏钻井成功率低，开发效果差，原因是对储集体规模及油水关系认识不清。而以渗流理论为基础的产量不稳定分析法不适用，且无法准确定量区分油与水的体积。本项目首先建立考虑渗流-自由流耦合及水侵影响的简化多尺度缝洞型油藏产量不稳定分析数学模型，建立边界控制流阶段曲线归一化无量纲参数表征模型，实现渗流-自由流耦合及水侵模型联合解析求解。然后，建立考虑渗流-自由流耦合油水两相流动特征离散缝洞网络产量不稳定分析数学模型，研究渗流-自由流耦合及两相流动界面表征处理方法，实现快速数值求解及参数反演。通过物模实验及数值模拟结果验证模型可靠性，编制评价软件。最后，进行现场应用，评价单井动态储量及水体大小，刻画油水界面，指导井位部署及措施调整。

缝洞型碳酸盐岩油藏储集空间多样，不同尺度的孔、缝及洞发育，各储集体普遍有水体但不具有统一油水界面。以渗流理论为基础的产量不稳定分析法不适用，且无法准确定量区分油与水的体积。本项目首先建立考虑渗流-自由流耦合及水侵影响的简化多尺度缝洞型油藏产量不稳定分析数学模型，建立边界控制流阶段曲线归一化无量纲参数表征模型，实现渗流-自由流耦合及水侵模型联合解析求解。然后，建立考虑渗流-自由流耦合油水两相流动特征离散缝洞网络产量不稳定分析数学模型，研究渗流-自由流耦合及两相流动界面表征处理方法，实现快速数值求解及参数反演。通过物模实验及数值模拟结果验证模型可靠性，编制评价软件。最后，进行现场应用，评价单井动态储量及水体大小，刻画油水界面，指导井位部署及措施调整。