Effect Of Inhibitors On Clay Mineral Combined Water

Sidewall instability problem often causes well drilling engineering come to a standstill, affects the geological data acquisition, the drilling cost, oil and gas field development process.etc, has been much attention in the field of petroleum drilling engineering. Rock mechanics properties degradation which is caused by hydration drop of clay minerals content is an important factor of borehole wall instability inducement, the borehole wall collapse of shale formation is due to the factor. Strong inhibitory drilling fluid can be a very good choice in this situation, while it can extend the period of borehole wall stability and create the space for efficient drilling, but there are still several instability problems of the formation (of the shale) with poor geological conditions. At this stage of the mechanical and chemical coupling research provides the foundation to solve such problems, but there is no breakthrough in the chemistry of the quantitative research, so the quantitative research on inhibitors of mud shale hydration effect is necessary.First,through the isothermal adsorption experiments of main clay minerals in shale content (montmorillonite、illite, kaolinite and chlorite), we found out the hydrophilic properties of the four kinds, montmorillonite got the strongest combined water adsorption capacity among them. Then combined with inflation rate experiments and XRD experiments, the inhibitors of montmorillonite hydration expansion and the influence of the crystal layer spacing dispersion were measured. Finally, hydration situation of the clay minerals and the mud shale are studied by thermogravimetric analyzer after injecting inhibitors, combining with the experiment data simulation we calculated the bound water of the shale.It was found that clay minerals content combined water adsorption was conducted in stages, which can be divided into strong combined water, weak bonding water, free water. Conventional volume expansion experiment can only test macroscopic inhibit effect, but not in-depth analysis of combined water suppression. XRD experiment confirmed that the salt inhibitor can enter the montmorillonite crystal layers, while polymer can only be wrapped in particle surface. Within the perspective of the inhibition effect of crystal layer spacing, salt inhibitor inhibiting effect is better than the polymer class. Thermogravimetric analysis can go deep into the water in the face of inhibitor performance research, discusses the inhibition mechanism of different inorganic and organic inhibitors also demonstrates the bound water is different from the properties of free water to the clay surface. Compared with the real mud shale water analysis, it was found that the theoretical calculation of the combination of the shale and its deviation is not huge, which means the theory value.