Abstract

The effectiveness of matrix acid stimulation treatments is limited in widely varying permeability zones due to poor diversion. A permeability zones due to poor diversion. A unique combination of nitrogen foam, oil-soluble resins and HEC diversion agents was developed to ensure complete acid contact throughout the multiple layer zones in a gravel packed offshore Gulf Coast Louisiana well. Through the use of radioactive tracers and on-line pressure monitoring of the tubing and annulus, onsite adjustment of diverter concentration at various points during the treatment was achieved. The diversion of acid throughout these widely varying permeability zones was proven effective based on two logging runs and observed surface pressure responses. The case history with supporting data is included in the paper.

Introduction

The effectiveness of matrix acid stimulation treatments are limited in widely varying permeability zones due to poor diversion. permeability zones due to poor diversion. Ineffective diversion was suspected in Well A after an unsuccessful matrix acid stimulation treatment. A unique diverter system was developed to ensure complete acid contact throughout the multiple layer zone in this gravel packed Gulf Coast Louisiana well. Through the use of radioactive tracers and on-line wellhead pressure monitoring, the diverter system could be varied during the job. At the end of the treatment the placement of the complete acid package was placement of the complete acid package was verified using a spectral gamma-ray log.

Well A was producing below expectation after initial completion when compared to offset producing wells. A matrix acid stimulation producing wells. A matrix acid stimulation treatment was pumped utilizing foam diversion and resulted in limited production increases. It was then decided to run a spinner production log to determine which lobe of this production log to determine which lobe of this reservoir was producing. The spinner log indicated that the upper half of the zone was contributing 100% of the flow while the lower half of the zone was not flowing (Figures 1 and 2). The density log which was run with the spinner indicated that the lower half of the wellbore was loaded with water, as shown in the left tract of Figure 2, listed as water occupancy.

P. 755

This content is only available via PDF.
You can access this article if you purchase or spend a download.