Innovative Method to Control Acid Placement during the Stimulation of Wells with High Water Cut

Abstract

Water production is a serious challenge when stimulating wells in mature reservoirs. Production results after acidizing sometimes reveal a higher water cut; in some cases this change is significant enough that the well is no longer able to flow unassisted. A typical acid stimulation in the field follows a predetermined pumping schedule, where diverter is squeezed into the high water cut interval prior to injecting acid into oil zones. The diverter volume is based on a rule of thumb and the acid is pumped after assuming that the diverter is efficiently sealing the high water cut zone. Several coiled tubing (CT) matrix stimulation jobs have yielded production results of 100% water cut.Prior to stimulation (a period of months or years), diagnostic logs were conducted to identify water producing intervals. Although, in some cases, the post-stimulation water cut may be as high as or higher than the water cut prior to the stimulation, suggesting that the diverter volume was not enough to seal the water zone. An innovative method is needed to confirm the isolation of high water cut zones before pumping acid, which would lead to increased oil production and reduce the risk of unintentionally stimulating water producing zones.

First Real-Time DTS Inversion Job Worldwide

“…Over the past years, the use of DTS has gradually been implemented as part of treatment workflows in an effort to help evaluating the effectiveness of those said treatments (Sierra et al 2008;Glasbergen et al 2009;Cantaloube et al 2010;Garzon et al 2010;Harbi et al 2011), The method usually consists in analyzing the evolution of the temperature profiles, typically acquired during the pumping stage and/or a post-stimulation shut-in period. Temperature fronts, as well as specific cool-down and warm-back features, are tracked and can yield valuable information as to fluid placement and fluid diversion.…”

A New Methodology for Stimulation of a High-Water-Cut Horizontal Oil Well through the Combination of a Smart Chemical System with Real-Time Temperature Sensing: A Case Study of South Umm Gudair Field, PZ Kuwait

“…Real-time DTS has been used recently in the context of matrix acidizing treatments to evaluate zonal coverage (Garzon et al 2010) (Cantaloube et al 2010) (Harbi et al 2011). This innovative approach enables engineers to deal with the uncertainty of predicting fluid placement along the well and to act in real-time following the interpretation of the DTS logs recorded during the treatment.…”