New Acid-Frac Techniques for Tight Reservoirs

According to some experts, the problem with acid-fracturing a low-permeability tight gas reservoirs is the problem of leaks into intercalated high-permeability zones or fluid loss through fractures, before the acid has had a chance to dissolve the calcium carbonate elements. This is particularly the case in dolomites, but also can happen in tight gas sands that have fractures and fissures.

The paper listed below suggests that a good leak-off control acid (LCA) would consist of he following:

Corrosion inhibitor
Corrosion inhibiting supporter
Fe(3+) stabilizer
Leak-off stabilizer
Gelled acid
Surfactant

Worth a try!

New formula for acid fracturing in low permeability gas reservoirs: Experimental study and field application
Journal of Petroleum Science and Engineering, Volume 59, Issues 3-4, November 2007, Pages 257-262
Z. Zhou, X. Wang, Z. Zhao, Y. Xu and K. Li

The SPE held a symposium on October 23 which appeared to be quite interesting. Entitled Field Management of Mature Reservoirs, the program seemed useful. I don't know if the proceedings will be available. The program is excellent:
http://www.spe.org/spe-app/spe/meetings/07APOL/2007/agenda.htm

Useful Resources:

Acidizing Oil and Gas Reservoirs: Cleansorb's Arcasol http://www.cleansorb.com/Acidizing_current_practice_and_Arcasolve_applications.html

Techniques: Schlumberger: Perf, acidize, and DST through the DST string
http://www.slb.com/content/services/perforating/tcp/application/stafdsta.asp