Simultaneous Gas-Solid Chemical Stimulation Of Hydraulically Fractured Oil Wells And Gas-Condensate Wells In Shales

What is this patent about?

’942 is related to the field of enhanced oil and gas recovery, specifically addressing the challenge of low recovery rates in hydraulically fractured shale wells producing oil and gas condensates. The background acknowledges that shale formations, while rich in hydrocarbons, suffer from low permeability, high oil viscosity, and unfavorable relative permeability, hindering efficient extraction. Existing methods, such as injecting surfactants in water, can exacerbate the problem by introducing water into the fracture system, further reducing oil mobility.

The underlying idea behind ’942 is to stimulate oil and gas production in shale wells by injecting a gas-solid mixture containing chemicals directly into the wellbore and fracture network. This mixture is designed to interact with the in-situ water present in the shale, altering the rock's properties near the fractures. The key insight is that by delivering chemicals in a gas stream, the method avoids introducing large volumes of water, which can block pores and reduce oil mobility. The solid chemicals, such as nanoparticles and surfactants , modify the rock's wettability, promoting oil flow through larger pores.

The claims of ’942 focus on a method comprising setting up a gas-solid mixing manifold at the surface, using a gas compressor to create a gas-solid mixture, injecting this mixture into the well to fill the wellbore and fracture networks, stopping the injection and shutting in the well for a soak period, and then opening the well to allow hydrocarbons to flow to the surface. The soak period is crucial, allowing the chemicals to interact with the in-situ water and the shale rock.

In practice, the method involves a cyclic process of injecting the gas-solid mixture, allowing it to soak, and then extracting the produced fluids. The gas compressor forces gas into a mixing manifold where solids (nanoparticles, surfactants) are introduced to form the gas-solid mixture. This mixture is then pumped downhole, filling the fractures created by hydraulic fracturing. The well is then shut in, allowing the chemicals to interact with the rock and water. Finally, the well is opened, and the produced fluids are extracted.

This approach differentiates itself from prior methods by delivering chemicals in a gas stream rather than a water-based solution. This avoids the problem of water blockage in the shale's pores. Furthermore, the cyclic nature of the process, with alternating periods of injection, soaking, and extraction, creates a dynamic pressure environment that enhances fluid flow from the reservoir to the well. The method aims to alter the rock properties near the fractures, rather than relying on slow diffusion of gases deep into the reservoir, leading to a more effective and efficient stimulation of oil and gas production.