Organic and inorganic deposits that accumulate near the wellbore create flow restrictions. These restrictions result in significant losses of crude oil and gas production and are a serious concern for operators. The organic deposits are mainly paraffins and asphaltenes that precipitate from the crude oil, due to various mechanisms (e.g., changes in phase equilibrium and composition). Typical treatments for these deposits include solvents and acids. More recently, microemulsion fluids have been used for production enhancement.

The objective of this work is to formulate a multifunctional treatment fluid that is able to remove organic and inorganic deposits in one step. This removal can be achieved by formulating a single-phase fluid-type microemulsion that combines the two immiscible treatments (solvents for organic deposit removal and an acid blend for scale removal) and surfactants, including water-wetting molecules.

Systematic evaluation of the microemulsion with various samples of organic deposits and crude oils demonstrates that this novel multifunctional microemulsion treatment fluid completely disperses deposits of paraffins and asphaltenes, breaks viscous emulsions and sludge, removes inorganic scale, and alters the wettability condition of the solids from oil-wet to water-wet.

A case history from a multiple-well field trial is presented that demonstrates the successful application of the microemulsion, with acid, to remove organic material and inorganic scale in oil wells.

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