The process of matrix acidizing, despite being one of the oldest operations in the petroleum industry, is still a challenge for tight carbonate reservoirs. This project considers the development of a multi-functional environment friendly chemical, for reservoir stimulation and formation damage remediation.
A microemulsion solution of biodegradable chelating agent is formulated, which is effective for tight carbonate reservoir stimulation even at high temperature. Together with the chelate based inorganic dissolver, aromatic naphtha as an organic dissolver is the other main active ingredient in the proposed microemulsion formulation. For this reason, the microemulsion solution can also be used to treat inorganic and organic mixed deposits which can involve in formation damage. The developed multi-application chemical is later tested for compatibility with reservoir fluids and production chemicals encountered during well flow back.
Formulations with low reactivity are required when the injection of stimulant is not possible at high rate. By making microemulsion with chelate, the reactivity and diffusivity of the chelating agent can be controlled further. Core flooding experiments on core samples from high pressure, high temperature and tight carbonate formation, are conducted to demonstrate wormhole formation during the matrix acidizing treatment with the formulated microemulsion. The synthesized stable microemulsion chemical is also subjected for detailed dissolution study on deep wellbore deposits of different composition from different fields. These inorganic and organic mixed deposits are otherwise hard to be remediated by aqueous or organic solvent alone.
The novelty of this article is in developing a chelate based microemulsion as the main stimulation fluid. Another uniqueness of the microemulsion solution is in the treatment of formation damage causing deposit species which are mixed in nature, without the need of any additives.