Applications of Mechanical External Casing Packers

Abstract

Field cases presented on this paper explain applications of Mechanical External Casing Packer (MECP) solving zonal isolation problems on openhole horizontal wells in Saudi Aramco. MECP is essentially a hybrid between existing cased-hole conventional packer and inflatable External Casing Packer (ECP). MECP is different than ECP in the mechanism energizing the sealing element. The packer is run as an integral part of the casing string to provide a seal between the casing and wellbore. Saudi Aramco has successfully used MECP controlling water production, isolating fractured open-hole sections, sealing casing shoe with leaking problem, and compartmenting openhole horizontal section. Included in this paper are four different field cases for openhole zonal isolation with MECP on horizontal wells. Each field case presents a particular application for the MECP. Technical data including well configuration and casing string are included in the paper. Field operations and lesson learned from each application are also presented in this paper. MECP has been successfully used for zonal isolation on openhole horizontal wells. Depending on the particular application, MECP can be run in combination with blank and/or screened pipe. Hole cleaning and wellbore conditions are factors affecting MECP placement. The knowledge provided in the paper can be applied to solving zonal isolation problems on openhole horizontal sections with different rock and fluid properties. The significance of this paper is that it presents actual field experiences and lessons learned for MECP applications. Furthermore, recommended field operations for successfully placing MECP on the well are also included in this paper. Introduction Mechanical External Casing Packers and External Casing Packers have been successfully used for solving different problems in drilling and completion operations in Saudi Aramco. Mechanical External Casing Packer description. Mechanical External Casing Packer (MECP) is primary a cementing and zone isolation systems utilizing a non-inflatable packing element (Fig. 1). The packer is run as an integral part of the casing string to provide a seal between the casing and wellbore. MECP has an elastomeric element which is set mechanically by shifting a balance sleeve allowing wellbore hydrostatic pressure to flood an atmospheric chamber and apply setting force to the non-inflatable element. The element is hydrostaticly set by mechanically shifting a sleeve, using an inner work string with a shifting tool on its bottom, and then mechanically locked.1 MECP is essentially a hybrid between existing cased-hole conventional and inflatable External Casing Packer (ECP).2 MECP was initially trial tested for zonal isolation on well A-41 at Heidrun field. Heidrun is located on the Haltenbanken area of the Norwegian Sea. The upper part of the reservoir is produced with aid of water and gas injection. Production from the lower part of the reservoir is based on water injection. Well A-41 has a 320 meter long 8–1/2 in. openhole section. The openhole liner consisted of 11 joints of Baker 5–1/2 in. Excluder coarse screen, one MECP and four additional joint of screen above the packer. No operational problem was reported during the trial test.2 MECP has been used, in combination with Inflow Control Devices (ICD) and blank pipe, to separate regions with different rock and fluid properties across the horizontal section. ICD were developed to create an uniform production profile along the entire horizontal section of the well.3, 4, and 5 ICD can be a pipe-joint with layers of different screen-size on top of each other (Fig. 2). ICD is designed to optimize production and delay water or gas coning in long, low-drawdown, high-rate horizontal wells.6, 7, and 8 External Casing Packer (ECP) Description. ECPs and Annulus Casing Packers (ACPs) are inflatable packers that are also run as an integral part of the casing string. They must be inflated during the completion installation. When inflated, they provide an annular seal between the casing and the wellbore or a previous installed casing string. The packers are designed for inflation with fluid (cement, drilling mud or water).9 As long term application requires cement inflation to minimize adverse effects on the packer, also the installation process is further complicated, especially in a highly deviated and horizontal wellbore.2, 10