Patent ID: 8210263
Filing Date: 2012-07-03
Classification: C09K

Abstract:
1. A method of changing the wettability of a rock formation previously contacted with an oil-based mud (OBM) comprising a non-polar fluid, the method comprising: pumping a water-wetting pill into the rock formation, where the water-wetting pill comprises forming in situ an in situ-formed emulsion from the in situ emulsion-forming components and at least some of the non-polar fluid of the OBM where the in situ-formed emulsion is a thermodynamically stable, macroscopically homogeneous mixture of at least three components, where the three components comprise a polar phase from the polar fluid, a non-polar phase at least partially from the non-polar fluid of the OBM, and the at least one surfactant, where the water-wetting pill further comprises an acid selected from the group consisting of mineral acids, acetic acid, formic acid, polyamino carboxylic acids, salts of these acids and mixtures thereof; changing the wettability of at least part of the rock formation to water-wet; and subsequently pumping a second pill into the rock formation where the subsequent pill comprises water.