Openhole ICD completion with fracture isolation in a horizontal slimhole well - Case study

Abstract

Abstract Preventing water or gas breakthrough and equalizing flow are two primary challenges that must be resolved when producing from horizontal slimhole wells. This paper discusses a "first-of-its-kind" concept used in a well owned by Saudi Aramco to prevent/delay water/gas breakthrough and to equalize flow across a 3-7/8-in. horizontal open hole. Inflow Control-Device (ICD)-type completions are desirable for slimhole horizontal redrills, and are a new completion design that combines the ICD-concept with swellable packers to compartmentalize the hole. The completion design was developed by a multidisciplinary team that had been assembled to review the latest technologies and to successfully bring the concept to reality. Swellable packers use rubber around the packer that will expand when introduced to hydrocarbons or water to permanently seal the annulus. The well, completed in a Middle East carbonate formation where natural fracturing is commonplace, employed a 2-3/8-in. pre-perforated liner and two swellable packers with blank pipe between to isolate a fracture. This fracture, had it been allowed to produce, would have been detrimental to well performance, and eventually, a costly workover operation would have been required. An additional swellable packer was included in the liner to compartmentalize the reservoir section below the fracture. The completion assembly was run into the open hole with a hydraulic disconnect tool, which included a fourth swell packer above to provide isolation inside the previous casing. The paper describes swellable packer technology and the well completion from concept evaluation to execution. In addition to the background information, the discussion will include the post analysis that used well rates and reservoir pressures to gauge the effectiveness of the final concept. The initial performance of this well met the operator's goals for good oil production with a stable water cut. Introduction Natural fracturing is believed to permeate most of the carbonate reservoir due to the brittle nature of the rocks. Today, most production wells are drilled as 6-1/8-in. horizontals and completed with 4-1/2-in. inflow control devices with openhole packers to delay and manage water production. A number of workover wells are drilled with smaller bit sizes. Consequently, this requires slimmer completion equipment to complete the wells in an optimum manner. Until recently, there has been a limited availability of packer and ICD sizes, and therefore, slimhole sizes had to be completed barefoot. (Al-Mumen et al., 2008). While proper planning is the key to risk management in any completion, slimhole well completions often have been considered much more difficult to plan because of the added challenges that they present. These difficulties include: "Smaller completion tools, which result in:Limited injection rateLimited sand volumeLimited treatment lengthsLimited kH treatability"High treating pressures due to friction in small workstrings"Limited production (flow rate) due to small tubulars"Limited availability of fluid-loss devices and effect on success rates (Sanford 2007).