Why is an unconventional hydrocarbon reservoir unconventional? An investigation into petrophysical and fluid composition controls.

为什么非常规油气藏是非常规的？

• 批准号: RGPIN-2018-05695
• 负责人: Harris, Nicholas
• 金额: $ 1.82万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=713822
• 关键词: Why; unconventional; hydrocarbon; reservoir; investigation

Unconventional petroleum reservoirs represent the largest fraction of remaining hydrocarbon reservoirs in the world. The most striking feature of these reservoirs, in addition to low permeability, is the unusual, unpredictable nature of fluid distributions: the lack of an obvious top seal and less dense (more buoyant) fluids underlying more dense fluids. Thus, gas or oil can accumulate in low permeability formations that underlie high permeability formations, and gas pools may underlie water or oil columns. Petrophysical properties and capillary forces clearly underpin the unusual distribution of fluids in unconventional petroleum accumulations, which are not found in high permeability formations. In multiphase systems, buoyant forces are balanced against surface tension at the fluid interfaces and the wettability of fluids on solid materials. Thus, shales seal hydrocarbons below a sandstone-shale contact, even though the overlying shale maybe water-saturated. If this applies to unconventional reservoirs, some combination of rock fabric (composition plus texture) interacts with fluid properties (buoyancy, composition, surface tension) to produce unusual segregations of fluids. But how fluid and petrophysical properties control fluid distributions is not understood. Four reservoir units provide natural laboratories for testing models that describe unconventional reservoirs: (1) the hydrocarbon-rich Montney Formation in western Canada that contains conventional hydrocarbon accumulations where it is shallow (distinct top seal, gas over oil over water) but unconventional accumulations where it is deep (no distinct top seal, variable and unsystematic fluid distributions); (2) the Upper Cretaceous large tight-gas-sand accumulations in the U.S. Rocky Mountains where lower permeability reservoirs underlie high permeability caprocks; (3) Lower Cretaceous tight oil/gas sandstones in Alberta with complex pore systems that require hydraulic stimulation to produce; and (4) Duvernay Formation, a shale liquids reservoir where rocks are variably oil-wet, water-wet and have mixed wettability in different parts of the reservoir. I will combine field data and quantitative modeling to develop models for fluid distributions in unconventional reservoirs and to identify tipping points that distinguish conventional from unconventional accumulations. Computationally powerful software can simulate migration of hydrocarbon fluids under the influence of both capillary and buoyancy forces. Such software has not previously been applied to unconventional petroleum systems and may require additional development. This analysis will, in the end, yield new, more precise models for hydrocarbon migration, trapping and distribution in unconventional petroleum systems, tested on important petroleum systems in Canada and the United States and globally applicable.

非常规石油储层是世界剩余的碳氢化合物储层中最大的一部分。除了低渗透性外，这些储层最引人注目的特征是流体分布的异常，不可预测的性质：缺乏明显的顶部密封和较少密度（更多的浮力）流体，其含量更高。因此，气体或石油可以在低渗透率的低渗透率形成下积聚，而渗透率高的形成构成，燃气池可能是水或油柱的基础。石油物理特性和毛细作用明确是基于非常规石油积累中流体的异常分布的基础，而在高渗透性地层中未发现。在多相系统中，浮力在流体界面处的表面张力和固体材料上流体的润湿性平衡。因此，即使上覆的页岩可能是水的饱和，页岩在砂岩 - 灯泡接触以下都密封碳氢化合物。如果这适用于非常规的储层，则岩石织物（成分加纹理）的某种组合与流体特性（浮力，成分，表面张力）相互作用，以产生流体的异常隔离。但是，尚不清楚流体和岩石物理特性如何控制流体分布。 四个储层单元为测试模型提供了自然实验室，这些模型描述了非常规的储层：（1）加拿大西部富含碳氢化合物的蒙特尼形成，其中包含常规的碳氢化合物在其浅层的地方积累（独特的顶部密封，在水上覆盖了较浅的天然气，在水上的气体），但没有易于常规的堆积（无常见的顶部密封且无易于分配，并且无易于分配，并且无易于分配，并且是无效的分配。 （2）在美国落基山脉的上白垩质大型高温岩石积聚，较低的渗透率储层是高渗透性山顶的基础； （3）在艾伯塔省的较低白垩纪紧密的油/燃气砂岩，其复杂的孔系统需要产生液压刺激； （4）Duvernay地层，一个页岩液体储层，岩石是可变的油湿，水湿的，并且在储层的不同部位具有混合性润湿性。 我将结合现场数据和定量建模，以开发非常规储层中流体分布的模型，并确定将常规堆积与非常规积累区分开的临界点。计算功能强大的软件可以模拟在毛细管和浮力作用的影响下烃流体的迁移。此类软件以前尚未应用于非常规的石油系统，可能需要额外开发。最终，该分析将在非常规石油系统中产生新的，更精确的模型，用于碳氢化合物迁移，捕获和分布，对加拿大和美国的重要石油系统进行测试以及全球适用。