Experimental evaluation of sandstone stimulation fluids for acid sludge prevention during oilwell matrix stimulation jobs

Abstract

Acid induced sludge can compromise matrix stimulation jobs performance in oil well interventions, it is associated to multiple sources including combinations of iron dissolved components, acid type and strength, certain crude oils and different type of additives such us surfactants, acid corrosion inhibitors, etc. Along with it generally comes changes in reservoir rock wettability and poor emulsion break which ends in emulsion blockage and that seriously compromises reservoir fluids recovery. The purpose of this study is the implementation of compatibility tests in different acid & crude oil proportions to find the appropriate additives and its concentrations to control acid induced sludge, shorten emulsion breaking times and avoid wettability changes. Two stimulation fluids at different acid strengths were successfully adjusted to prevent sludging tendencies finding ferric iron inhibitors, anti-sludge agents, mutual solvents, and surfactants as critical materials to prevent and control sludge formation prior to job executions

Keywords

• stimulation fluids; sludge prevention; matrix stimulation; well intervention; acidizing jobs: mutual solvents; iron control