Underground imaging in real time by using white noise reflection processes: application to petroleum recovery including oil sands

重复地震射孔，通常被称为4D地震，用于了解油气开采过程的原位演化。例如，对于油砂储层的热采过程，如蒸汽辅助重力排水（SAGD），可以使用重复的地震拍摄来确定储层内蒸汽室的生长情况。蒸汽室的均匀性直接关系到出油量和工艺效率：蒸汽室越均匀，出油量越大，排放到大气中的温室气体量就越低。需要通过4D地震对蒸汽室进行连续监测，以查看蒸汽室的演变情况，从而最大限度地提高产油量并减少排放。然而，地震数据的采集和解释需要较长的处理时间，其空间分辨率约为10 m。因此，地震方法在估计储层（如页岩层和其他流障）的腔室大小、形状和内部不连续方面存在很大的不确定性。在此，我们建议继续发展白噪声反射技术，以实时成像地下储层及其非均质性在米级或更小的分辨率。白噪声反射技术能耗低，可以快速分析，实现石油开采过程的实时监测，并且可以实现4D地震方法无法实现的分辨率。到目前为止，白噪声反射已经通过详细的热声油藏模拟应用于SAGD过程，并在实验室中使用大型物理模型设备进行测试。模拟和实验室测试的结果表明，与地震方法相比，该技术具有在更低功率水平和更高频率下成像储层的潜力。由于该方法使用正交编码信号，因此来自采油过程和原生储层环境的噪声不会干扰监测。需要资金才能进入下一阶段：实地测试。一家大型石油服务公司已经同意参与该油田的技术测试。

Repeated seismic shoots, often referred to as 4D seismic, are used to understand the in situ evolution of oil and gas recovery processes. For example, for thermal recovery processes for oil sands reservoirs such as Steam-Assisted Gravity Drainage (SAGD), repeated seismic shoots can be used to determine how the steam chamber grows within the reservoir. The uniformity of the steam chamber is directly related to the amount of oil produced and the efficiency of the process: the more uniform the steam chamber, the larger the amount of oil and lower the amount of greenhouse gases emitted to the atmosphere. Continuous monitoring, done by 4D seismic, of the steam chamber is required to view steam chamber evolution to maximize oil produced and minimize emissions. However, seismic data acquisition and interpretation requires extensive time for processing and its spatial resolution is of the order of 10 m. Thus, seismic methods have large uncertainties associated with estimates of the chamber size, shape and internal discontinuities in the reservoir such as shale layers and other flow barriers. Here, we propose to continue our development of white-noise reflection technology to image underground reservoirs and their heterogeneity at resolution of the order of meters or smaller in real time. White noise reflection technologies are low energy, can be analyzed quickly enabling real-time monitoring of oil extraction processes, and allow resolutions down to length scales not yet achieved by 4D seismic methods. To date, white noise reflection has been tested by using detailed thermal-acoustic reservoir simulation with application to the SAGD process and in the lab by using a large physical model apparatus. The results from simulations and lab testing reveal that the technology have the potential to image reservoirs at lower power levels and higher frequencies than seismic methods. Since the method uses orthogonally-coded signals, noise from recovery processes and the native reservoir environment do not interfere with monitoring. Funding is required to go to the next stage: testing in the field. A large oil services company has agreed to participate in testing of the technology in the field.