Methods of Sludge Control During Acid Stimulation Treatments

Abstract

The formation of asphaltic sludge during acid stimula- tion has been a serious problem in man:r areas for sel'era) ,rears_ Such sludge:;; han· had ad,"erse effects on the re- suUs of treatments in se\"eral Canadian resenoirs_ Recent studies ha"e shown that sludl-:"e rna}' also affect results in many are,lS where its effects ha"e not l'et been recog-nized. These studies indicate that: L-Sludge is a precipitate of colloidal materials pres- ent in crude oils. 2.-The preeipitates occur due to changes in the en- vironmental conditions of the crude b}' the addition of materIals such as acid. 3.-0nce formed. sludl:!:e is insoluble in most treatin::r chemicals. .J.-Sludge can be preH"nted or contrOlled by the use of stabilizinJ,! agents in treating flUId or by the use of certain soh'ents as the outer phase of ac.id-in~oil emulsions. The purpose of this paper will be to show how and why slud~e is formed and how it can be pre\'ented or con- trolled. Simple laboratorJ- tests t(] determine the probabil- ity of sludge formation prior to treatment are discussed. Aetnal field results point out some of the problem areas in Canada and show that slud~e control durin~ acidizing treatments can increase producth'ity in these areas_ INTRODUCTION