Conceptual design and development of a non-invasive drilling, well completion and well stimulation fluids

在钻井、完井和增产作业中，油气井的产能会因地层损害而显著降低。复杂的岩石/流体相互作用削弱了油井的产能。在大多数情况下，损坏的油井会定期关闭进行清理。纠正损害会导致延迟，可能需要昂贵的油井增产操作。将研究两个新的非侵入流体概念在油气井中的适用性：使用微泡作为桥梁机制的流体；以及在流经多孔介质时产生高摩擦压力损失而不会在油井中流动时产生过多损失的流体。微泡具有独特的能力，可以在储层的孔隙中形成一座桥梁，阻止流体入侵。通常情况下，桥接机制是通过“贾敏效应”来解释的，“贾敏效应”描述了一种非润湿流体将润湿流体推入毛细管空间所需的压力。由于微泡结构和性质的复杂性，目前尚不清楚这种效应到底在什么条件下发生。因此，本论文将从实验和理论两个方面对微气泡的桥联机理和微气泡控制流体滤速的效果进行研究。粘弹性流体在多孔介质中的流动过程中观察到的压降是流体剪切和拉伸粘度的强烈函数。对于粘弹性流体，拉伸粘度可能比剪切粘度大几个数量级。这将导致压力损失的巨大增加，这通常被归因于内部蛋糕的形成。将进行实验和理论研究，以考察拉伸粘度对流体滤失率的影响。如果能有效地将钻井、完井和增产作业造成的产能损害降至最低，就可能实现显著的储量增加。非侵入性流体技术是释放额外资源的关键之一。如果不能充分开发这些新技术，将导致错失机会，并使潜在的有价值的碳氢化合物储量“在经济上陷入困境”。

Productivity of oil and gas well decreases significantly due to formation damage that occur during drilling, well completion, and well stimulation operations. The productive capacity of wells is impaired by complex rock/fluid interactions. In most cases, the damaged wells are shut down periodically for cleaning. Rectifying the damage causes delays and may require expensive well stimulation operations.  Two new non-invasive fluid concepts will be investigated for their applicability in oil and gas wells: fluids employing microbubbles as bridging mechanisms; and fluids which generate high friction pressure losses when flowing through porous media without generating excessive losses while flowing in the well. Microbubbles have the unique ability to form a bridge in the pores of the reservoirs which stops fluid invasion. Commonly, the bridging mechanism is explained through the "Jamin Effect" which describes the pressure needed for one non-wetting fluid to push a wetting fluid into a capillary space.  Due to the complexity of the microbubble structure and nature, it is unknown under exactly what conditions this effect takes place. Therefore, experimental and theoretical studies will be conducted to investigate the mechanisms of bridging, and the efficiency of controlling fluid filtration rate by using microbubbles. The pressure drop observed during the flow of viscoelastic fluids through porous media is a strong function of the fluid shear and extensional viscosity. For viscoelastic fluids the extensional viscosity may be several orders of magnitude larger than the shear viscosity. This will lead to a tremendous increase in pressure loss, which is very often attributed to the building of internal cake. Experimental and theoretical studies will be conducted to investigate the effect of extensional viscosity on the fluid filtration rate. Significant reserve additions may be realized if the productivity impairment associated with drilling, well completion, and stimulation operations can be effectively minimized. Non-invasive fluid technologies are one of the keys to unlocking additional resources. Failure to fully exploit these new technologies will result in missed opportunities and leave potentially valuable deposits of hydrocarbons "economically stranded."