|Stimulation and other treatment fluids generally require a variety of chemical additives to achieve the desired performance properties and to prevent or minimize potential problems. In acid stimulation this package of additives usually consists of at least a corrosion inhibitor, iron control additive, low surface tension/capillary pressure surfactant and, for oil reservoirs, a non-emulsifier. In addition additives for friction reduction, diversion, acid induced sludge prevention, clay and fines stabilisation, precipitation control, viscosifiers and fluid loss additives may be required. It is crucial that these additives are compatible with each other, the formation and the formation fluids. Compatibility testing can include a variety of different methods.
|Incompatibility of additives can be investigated by mixing and heating the treatment fluids including all additives to the required temperature. Signs of incompatibility include for example clouds, precipitates, phase separation, and changes in pH, color or viscosity. A pressurized see-through cell is available for evaluation at higher temperatures.
|These tests can be used to verify the compatibility of treatment fluids with each other or with the native formation fluids. They can also be used for optimization of for example surfactant, mutual solvent and sludge control additives. The test fluids are mixed in a certain ratio and an emulsion is induced. The sample is then heated and the demulsification is monitored as a function of time.
|The compatibility of treatment fluids with the porous media can be evaluated by conduction a core flow test. Please refer to the Acidizing page for more information regarding this technique.|