In September 2010, an Operator had drilled and completed a horizontal well in the Ratawi Oolite formation with a 3,000 ft, 8.5-in. open hole lateral at 6,650 ft true vertical depth (TVD). Initial production from the well was 1,450 BOPD with an electric submersible pump (ESP), but soon after being put on line the production declined. Several coiled tubing (CT) acidizing treatments were performed in an attempt to restore productivity. However, due to the formation heterogeneity, limited zonal coverage and inconsistent acid distribution, these treatments resulted in limited improvements to productivity.
The production performance plot (Figure 1) demonstrates the decline of oil production (October 2011 to September 2012) after the first CT acid stimulation job. The well had several workover jobs, such as pump flushing, general ESP well service and water shutoff, resulting in increased oil production before decreasing (November to December 2012) until it stabilized at an average 340 BOPD.
The Operator was faced with the challenge to select the most appropriate re-completion/stimulation technology that could achieve the following objectives: 1) Effectively and evenly stimulate the entire horizontal section, 2) Benefit from the vast network of natural fractures within the formation matrix to further enhance production, and 3) Maintain wellbore integrity.