To date, more than 100 sandstone-acidizing treatments have been performed in several Colombian oil fields, targeting the Villeta and Caballos Formations in the Putumayo Basin. Fines migration has been the main damage mechanism treated with this type of chemical stimulation. This paper summarizes a wide variety of sandstone-acid-stimulation case histories, highlighting aspects such as mechanical conditions and operational practices.
The Putumayo Basin is located in southern Colombia. The Putumayo Basin shows a stratigraphic sequence containing Early Cretaceous (marine) to Miocene/Pliocene sediments (fluvial). Fig. 1 above illustrates the location of the Putumayo Basin.
The T Sand samples examined are fine-to medium-grained sandstones. They are composed primarily of quartz grains cemented primarily with quartz overgrowths and authigenic clays. Rare-to-minor cements include solid hydrocarbon, pyrite, and dolomite. X-ray-diffraction (XRD) analyses show that all of the sandstone samples are composed primarily of quartz and clay minerals.
Feldspars are absent from all but one sample. Given that virtually all of the framework grains are quartz, with possibly minor argillaceous grains, the sandstone is classified as quartzarenites. Scanning-electron-microscope (SEM) photographs show authigenic kaolinite filling intergranular zones and possibly replacing grains....
Removing Fines-Migration Formation Damage in the Putumayo Basin in Colombia
01 February 2017