New Acid Simulation Era: Matrix Acidizing as Sandstone ad Limestone with Chelating Acid System

Abstract

Rimau asset produced oil and gas from Limestone reservoir and Sandstone Reservoir. Acidizing job for mature field hold essential job for production surveillance and optimization. Acidizing on those different reservoir types, have own acid recipe designed for each reservoir uniqueness.
Each Acidizing type, either Carbonate Acidizing with regular Acid HCl or Sandstone Acidizing with HCl-HF recipe, facing its own challenging problems. Likewise face dissolution problem (mainly at HCl Limestone acidizing), Corrosion and iron precipitation,
second reaction and precipitation (mainly at HCl-HF Sandstone acidizing), and limited mineralogy reservoir data to assist acidizing design. Those challenging problems, will have no issue by Chelating Acidizing System. And it works either at Sandstone or Limestone without further additional cautions.
Result of Chelating Matrix Acidizing in Rimau, show production increase. In term of job cost, Chelating Acidizing have fairly same cost with regular Acid. Furthermore, Chelating is less hazardous than HCl Acidizing and HCl-HF Acidizing. Chelating is friendly with
downhole metal equipment. So it won't create damage in sub surface equipment, due to long exposure contact.
Before used for oil field purpose, chelating especially EDTA used for lab titration purpose, for Calcium (Ca) analysis in water hardness test. Chelating especially EDTA is also well known in medical used. In oil field, chelation is used to enhance stimulation treatments, scale removal, and to clean surface facilities. This Chelating purpose in oilfield, especially EDTA at matrix stimulation. First investigated in 1997 by Fredd and Fogler.