Novel Perforation Job Design Leads To Successful TCP Shoot In A 3000 Foot Horizontal Carbonate Producer

Abstract

Abstract A recent horizontal producer well was drilled as part of a multilateral openhole completion pair in the Arabian Gulf area. The casing of the main wellbore could not get to bottom which necessitated the bottom lateral be cased and cemented for isolation purposes and then perforated. The decision to perforate the 3000' horizontal section was unexpected so supplies were insufficient to perforate this long section using the traditional perforating method. Rather than delaying the well completion and deferring production from this well, an effort was put into looking for alternatives. With the help of a perforation modeling tool it was shown that the horizontal section could be shot using a dynamic underbalance job design at greatly reduced shot densities and still achieve an injectivity, required for acid matrix stimulation, and subsequent productivity greater than if the well were to be shot conventionally at 6 spf. This technique of dynamic underbalance had been successfully used locally on wireline perforating jobs in short intervals but never on such a long well section nor at such low shot densities. Another potential complication with the conventional perforating technique is the presence of a 2nd open hole lateral which was in communication with the well to be perforated. This meant that the zone would be shot in an overbalanced condition which can lead to post perforation damage and poor injectivity. This paper will describe the process used to establish the dynamic underbalance perforation job design suitable for this well, the final job design, the execution of the job and the obtained results of this successful application. The results indicated better than expected injectivity prior to acid matrix stimulation and better than expected well productivity post stimulation. The improved well productivity is based on modeled and also nearby well production results. A successful job design methodology and execution has been tried for the first time in this region and has potential applications to many other wells. Background The horizontal well that forms the basis for this case study was drilled offshore in the Arabian Gulf in 2007. The well was intended to be completed as an openhole producing well and the case under consideration here was one of 2 lateral drains (Figure 1). During the well construction process the 7" casing was set at higher than planned depth leaving a part of upper reservoir in communication with lower reservoir below the 7" casing shoe. This reservoir section would interfere with the production from the lower 6" hole so it was decided to run a 4 ½" liner and extent it up into the 7" casing to provide isolation between the two laterals. With a cemented liner in place this necessitated the requirement to perforate the liner section in order to produce the well.