Study On Preparation And Reusing Method Of Slick Water Fracturing Fluid In Shale Reservoir

Shale reservoir has characters of low permeability、huge thickness、natural fracture growth bad, only after hydrofracture can it have value of industrial exploit. The conventional fracturing fluid system is not suitable for reservoir fracturing of shale oil and gas, at present, the widely used fracturing fluid in shale reservoir is slickwater fracturing fluid. Slickwater fracturing fluid is divided into surfactant slickwater fracturing fluid and polymer slickwater fracturing fluid. Among them, polymer slickwater fracturing fluid can keep the drag-reducing effect stable, and also has good characters of low cost、high drag-reducing ratio、slight environmental pollution after returning back from reservoir. So now the mainly used slickwater fracturing fluid is polymer slickwater fracturing fluid. This paper mainly has a study for polymer type slickwater fracturing fluid about the optimization of the drag-reducing agent major component、the method to make the polymer type drag-reducing agent dissolve quickly、compatibility and the method to make the slickwater fracturing fluid reusable.With different molecular weights of polymer and different types of polymer as the raw materials for the drag-reduction agent optimization of main components.Finally, choose the drag-reducing agent PEO(2 million) as the best drag-reduction agent,as a mainly drag-reduction agent composition that laboratory use to prepare slickwater fracturing fluid. Due to the determined drag-reduction agent belongs to high polymers, it face problem when dissolved in water.We have a research about the method to make the drag-reducing agent from the form of pink become the type of sizing agent. Verified by the experiments that the method of making the drag-reducing agent become the type of sizing agent is a effective way to help the drag-reducing agent dissolved quickly.Aimed at the optimization best drag-reduction agent PEO(2 million),testing the effect of temperature and salinity to its property.We can attach the conclusion that effect of temperature and salinity to the optimization best drag-reduction agent’s property is slightly. Through compatibility evaluation, found that the drag-reduction agent PEO(2 million) with other fracturing additives、the formation water from spot and the crude oil from spot have good compatibility. Through core damage evaluation of the drag-reducing agent PEO(2 million) found that the damage which drag-reduction agent PEO(2 million) do to the core damage is so slightly.Have a research about the method to make the slickwater fracturing fluid which returning from reservoir reusable, determining the best handing solution of returning slickwater fracturing fluid returning from reservoir is to additive another distribution of drag-reduction agent(PJZJ-3:PEO(2 million) is 3:1), the additive quantity is 0.05%.Through this solution, the slickwater fracturing fluid which returning from reservoir can performance effectively again.