First Horizontal Openhole Gravel Pack Installation in a Clastic Gas Reservoir: KM Field

Abstract

The KM field is part of the KM cluster development project, which plans to deliver 100 MMscf/D of gas to liquefied natural gas (LNG) from five horizontal wells. Four of the wells were completed with 4 1/2-in. production tubing using horizontal openhole gravel packs (HZOHGPs) as sand control, which was the first application of this technology for the operating company. Based on geomechanical modeling, the KM field is an unconsolidated clastic gas reservoir that requires active sand control. The particle size distribution (PSD) suggests that the KM clastic formation is a poorly sorted sand with a high uniformity coefficient and very high fines content; thus, justifying the need to use a gravel pack completion rather than a screen-only completion. The conventional internal gravel packed (IGP) technique has been widely applied because it provides a reliable means of abating sand production. However, it does not provide the same productivity as a HZOHGP. IGP is also highly prone to increasing skin throughout the production life of the well. Nodal analysis indicates that HZOHGP would give the highest production index (PI) with low production drawdown compared to a cased-hole gravel pack completion, in addition to potential cost savings realized from the elimination of the casing, cementation of the casing, and perforation of the casing. Running a screen in conditioned, solids-free mud, avoiding premature bridging during the job execution, proper removal of the mud filter cake, and limiting flow to below critical drawdown pressure (CDP) play important roles in the successful implementation of a HZOHGP completion in the KM field. This paper describes the planning of the first openhole gravel pack installation for an unconsolidated gas formation while highlighting the risk assessment, the lessons learned, and the excellent production performances achieved. Use of OLGA® transient simulators for estimating drawdown during well cleanup is also briefly discussed.