Laboratory studies on the selection and testing of chemical compositions
Each field (implementation object) has a different composition and properties of the formation and reservoir fluids, which requires an individual approach to chemical composition selection. Taking into account the reservoir characteristics (temperature, permeability, TDS, etc.), pre-selection of chemical compositions samples is carried out. In order to clarify and select the optimal one in terms of technological efficiency and cost, it is necessary to conduct a set of laboratory studies.
In case of selecting a chemical composition for polymer flooding, implementation of the main studies are:
Rheology&stability studies:
— input control of polymers, determination of active content, intrinsic viscosity, hydrolysis degree, molecular weight of the samples;
— determination of the dissolution time and the amount of undissolved solids when the polymer is dissolved in water from the RPM system;
— rheological curves plotting (determination of the dependence of the polymer solution viscosity on the concentration and shear rate);
— assessment of thermal and mechanical degradation of polymer solutions;
— determination of static adsorption of polymer samples;
Filtration studies:
— evaluation of dynamic adsorption of polymer samples;
— determination of displacement efficiency, resistance factor and residual resistance factor;
— evaluation of the mechanical degradation of the polymer solution when passing through the porous medium of the reservoir model.
When selecting a chemical composition for surfactant-polymer flooding, the following types of research are additionally performed:
Rheology&stability studies:
— input control of surfactants, assessment of appearance, pour point, density, mass fraction of the active content;
— assessment of surfactants solubility and compatibility with produced water and water from the PRM system;
— determination of the dependence of the interfacial tension on the concentration of surfactants;
— assessment of phase behavior (determination of microemulsion types);
— assessment of compatibility with polymer;
— determination of the thermal stability of the surfactant-polymer formulation.
Filtration studies:
— determination of the surfactant-polymer composition displacement efficiency;
— relative permeability determination after chemical injection;
— determination of dynamic adsorption of surfactant polymer composition.
* — the above list is general (depending on object conditions and project design can be adjusted).