Study On The Stability Of Heavy Metal Ions In Formation Water During The Process Of Water Shutoff In Oil And Gas Production By Graphite Oxide

Chemical liquid is been in many working steps during the process of mining oil and gas, especially in the process of mining, fracturing and profile control and water shut-off. In order to achieve the performance of the working fluid, a variety of heavy metal ions is been used as functional additives. As the mining process, the heavy metal ions are constantly brought into layer. They will be absorbed by the layer and move along the way. The heavy metal ions could cause potential harm on animals and plants, when they move into the surface of the ground or the groundwater. Regarding the issues above, we can draw support from chemical water shutoff at oil and gas mining process to reduce the excretion of heavy metal ions. So we can reduce the concentration of heavy metal ions when we deal with the polluted water on the ground. We can use graphene oxide which has high specific surface area and rich surface functional groups to achieve this purpose. The main results were listed as follows:(1) The traditional method to synthesize graphene oxide "Hummers" was been improved: after the mid-temperature reaction finished, high-temperature stage was canceled and the reaction was continued at 35℃, in order to assure the reaction was occurred in more safe condition.(2) Base on the rule of pH changing as the change of the lateral size of graphene oxide, by controlling pH of graphene oxide water solution, it was feasible to synthesize graphene oxide sheets with controlled lateral size to achieve lateral size of graphene oxide sheets controllable optional operatio.(3) Through the study of breakthrough curve of graphene oxide, we get the result of Zeta and the average particle size with graphene oxide at different ion concentrations. At the same time, we calculate the graphene oxide’s retention in the core through the curve. According to the above conclusions, combining with the theory of DLVO, we discusses the action mechanism of graphene oxide in layer and the mechanism of interaction with heavy metal ions.(4) Through the absorption experiments of graphene oxide with Cd(NO3)2, Pb(NO3)2 and K22Cr2O7, taking Atomic absorption spectrophotometry, we determine the concentration of the liquid before and after the experiment. We calculate the removal rate of graphene oxide to these heavy metal ions, discusses the experiment result of the mechanism of the absorption of graphene oxide to heavy metal ions. In order to simulate the stabilizing effect of graphehe oxide to detained heavy metal ions during the chemical water shut-off process, the paper designs the absorption experiment. By the experimental results and analysis, we can know that graphene oxide synthesized by the modified Hummers method could removal heavy metal ions effectially.(5) Taking core flow experiment and designs single core experiment and Dual core parallel experiment. Determining the resistance coefficient graphene oxide and the residual resistance coefficient of graphene oxide, doing the research about the influence of the flow rate of different permeability cores after the graphene oxide is injected into the core. The results show that graphene oxide can penneate in high permeability cores, reduce the capacity of permeation of high permeability rocks and reduce the water flow of high permeability rocks, obtaining the water shut off performance. Because the high adsorption capacity of graphene oxide to heavy metal ions, we can take the advantage of the step of chemical water shut off to reduce the exhaust of heavy metal ions, and reach the goal of concentration of input of heavy metal ions in the process of disposal of water.