Matrix acidizing in sandstone formations
AssigneeMobil Oil Corporation
InventorAlfred R. Jennings, Jr.
Life of this patent
Estimating the term…
Abstract
A method for improved matrix acidizing of a sandstone formation containing a perforated well. Initially, a "pre-pad" and a temperature stable viscous gel pad are pumped into the formation via said well at injection pressures greater than 5 BPM while monitoring surface pressures. Next, an acid suitable for acidizing the formation is pumped into the formation while the injection pressure is maintained. Thereafter, additional stages of viscous pad and acid are pumped into the formation to ensure zonal coverage and acid-stimulation.
Claims21
A method for improved matrix acidizing in a sandstone formation comprising:
- a) injecting a pad of viscous gel via a perforated wellbore into at least one high permeability interval or zone of the formation at a rate sufficient to cause a fracture therein to remain open so as to facilitate acid circulation around clay damage in the interval or zone while also cooling said zone;
- and
- b) injecting thereafter a liquid acid into the formation at a rate sufficient to the enter said interval equally as the pad restrains the flow of acid in said interval or zone thereby prolonging the acid's contact time and reactivity thereby removing clays which have damaged said interval and restoring the permeability thereof.
A method for improved matrix acidizing in a sandstone formation comprising:
- a) injecting a pre-pad of a salt solution into desired intervals of the sandstone formation via a perforated wellbore that fluidly communicates with said interval;
- b) injecting a pad of viscous gel via the perforated wellbore into at least one high permeability interval or zone of the formation at a rate of at least about 5 BPM that is sufficient to cause a fracture therein to remain open so as to facilitate acid circulation around clay damage in the interval or zone while also cooling said zone;
- and
- c) injecting thereafter a liquid acid into the formation at a rate of about 5 BPM which is sufficient to the enter said interval equally as the pad restrains the flow of acid in said interval or zone thereby prolonging the acid's contact time and reactivity thereby removing clays which have damaged said interval and restoring the permeability thereof.
Dependencies are inferred from the claim text.