Successful Application of Novel Modified HF Acid System for Sandstone Matrix Acidizing in B Field

Abstract

Fines migration is the common formation damage mechanism in the sandstone reservoir of field B which has less established information on mineralogy distribution. There were many attempts to remediate the formation damage using conventional mud acid fluid system but resulted in mixed success rates. This situation warrant for the need for a modified acid recipe to avoid aggravation of fines migration problems in this field post acid treatment. This paper presents the pilot application of a modified HF acid recipe incorporating chelate. The paper also depict the evaluation process that includes candidate selection, laboratory workflow and results, treatment design, execution strategy and the post job analysis on well B-1S. In order to increase the acid stimulation success rate, the team analyzed numerous post job reports of the nearby wells that were previously treated with conventional mud acid system. The root causes of the previous job failures were identified, such as prolonged soaking of acid in the formation due to unplanned platform shutdown and limited platform deck space. Taking these factors into account, the modified HF acid system (with 1.0% HF) was selected for execution in B Field. The pilot execution resulted in double the production compared to the pre-treatment rate. The modified HF acid system has also improved the economics of the project due to its lower cost since it is a one-step system and has lower additives requirement.

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“…Nowadays, the academy and industry have focused on developing new technologies to improve acid stimulation in sandstone formations to mitigate the critical issues associated with the high reactivity of the acid solutions. − Most studies are focused on acid reformulation with chelating agents, solvents, and dispersants to increase the performance for fines removal . However, these new molecules increase costs, could lead to corrosion issues in the production system, and cause the formation of emulsions. − One innovative alternative is the encapsulation of acid solutions, which shows a huge potential due to the increase in the acid penetration, the control over undesirable reactions, and the reduction of the corrosion issues without lowering the acid efficiency. − …”

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“…A chemical method of stimulation of oil and gas wells is the most mature and widely applicable method for acceleration of oil and gas production worldwide [1][2]. However, despite almost a century of experience in development of chemical methods for reservoir stimulation an industry still requires technology improvement [3][4][5][6][7]. Firstly, a reservoir stimulation technology improvement is always relevant, because of dynamics of oilfield development lifecycle [8][9].…”