Technology Update: Completion Methods Analyzed in Two US Unconventional Plays

Abstract

Technology Update The information in the article is based on paper SPE 176984, which was presented at the 2015 SPE Asia Pacific Unconventional Resources Conference and Exhibition in Brisbane, Australia, 9–11 November. An operator in the United States midcontinent region systematically analyzed different completion technologies and identified openhole multistage (OHMS) systems as a more cost-effective method than the cemented casing plug-and-perf (CCPP) techniques, used on previous wells, for increasing production and reducing development costs. The operator holds one of the largest acreage positions in the region and in 2014 had operated or participated in approximately 170 horizontal wells. The operator’s development focused mainly on the Mississippian Lime play in northern Oklahoma and the Marmaton play in the Oklahoma and Texas Panhandles. Each carbonate resource play required a thorough evaluation to assess the unique geologic characteristics and thoughtful application of technology to unlock significant amounts of previously untapped oil and gas deposits. These plays are composed of a mix of unconventional shale, carbonate, and sandstone plays. When developing its assets, the operator focused on creating a productive well, then on improving production and well cost. The steps taken by the operator included the following: comparing different completion methods analyzing completion costs implementing new technology to improve completions studying microseismic data to confirm assumptions and fine-tune completion design conducting tracer analysis to ensure all stages were contributing to production Lessons learned from each well were applied to future wells, and the operator realized further cost savings as it continued development of the region using OHMS completion systems. These cost reductions were achieved while preserving the estimated ultimate recovery (EUR) of the assets, increasing the economic viability of the operations. Completion Methods Compared The first objective was to determine which major completion function had the most effect on production and then on cost. Completion equipment is a major function of this aspect, and currently there are two main completion methods being used in the two plays: OHMS completion systems and CCPP methods. The main difference between OHMS and CCPP systems is when the liner is picked up and run into the lateral section (Snyder and Seale 2011). In OHMS completion systems, the lateral section is left as uncemented, and fracture ports and isolation packers are run into the well as part of the liner. The well is stimulated in one continuous pumping operation, using size-specific actuation balls to open the fracture ports and provide isolation inside the liner between stages. In CCPP completions, a liner is run into the wellbore and cemented in place. The cement provides annular isolation, while a series of bridge plugs provide isolation inside the liner between stages. Several trips are required in and out of the wellbore to shoot perforation clusters in the liner and set bridge plugs for each stage.