Applications of Acid Fracturing Technique to improve Gas Production in Naturally Fractured Carbonate Formations, Veracruz Field, Mexico

Abstract

This paper presents the results of successful applications of Acid Fracturing to increase gas production in mature carbonate fields in Mexico. Production comparisons show a substantial improvement in well performance following acid fracturing treatments. Six case studies are provided where a systematic methodology was employed to correctly determine candidates, and treatments. The methodology discusses the use of a novel technique that consist in alternating stages of acid and a non reactive fluid. The fracture acidizing treatment technique, is designed to stop wormhole growth once growth has begun. The technique consists of initiating a fracture with a nonreactive pad of gel led fluid followed by alternating stages of alcoholic acid and nonreactive pad. This system has been chosen to overcome two main problems, those are fracture extension and well cleanup. This technique improves live acid penetration in a naturally fractured reservoir, thus sustaining greater and longer production increases than prior stimulation treatments. The benefit obtained from the used of alcoholic acid as a reactive fluid in gas wells is observed during the initial production stages, when the well cleanup is rapidly achieved and gas production established. Results of the treatments performed are discussed in details, including acid and gel volume, designs and analysis of the pressures recorded during placement, also data on load recovery times following the job are shown as wells as Prior and post fracture well analysis interpretations showing effective skin reduction and fracture length. Finally gas and condense production are presented including stability with time. P. 285

The pilot appraisal of acid fracturing of coalbed methane reservoir in southeast Qinshui Basin, China

“…Despite the fact that acid fracturing has been proved as an important way to improve oil and gas production for carbonate reservoir with natural fractures (Hill & Schechter, 2000;Perex, D, Huidobro, E., & Avendano, 1998), it has not been applied universally in the stimulation of CBM wells. It was reported that small volume of acid spearhead ahead of the main fracturing had been implemented to clean out the cement deeper into near well bore area and reduce the breakdown pressure of a few CBM wells (Adil, Sharma, & Bhat, 2012).…”