Redevelopment of the Cardium Formation by Use of Fractured Horizontal Wells

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 137737, ’Re development of the Cardium Formation Using Fractured Horizontal Wells: Res er voir-Engineering Perspectives and Early Case Histories,’ by E.N. Omatsone, M.A. Bagheri, SPE, and C.M.F. Galas, SPE, Sproule Associates; B. Curtis, Bonterra Energy; and K. Frankiw, Midway Energy, originally prepared for the 2010 CSUG/SPE Canadian Unconventional Resources & International Petroleum Conference, Calgary, 19-21 October. The paper has not been peer reviewed. The full-length paper presents a brief review of the historical performance of vertical wells in the low-reservoir-quality areas of the Cardium formation and describes the effect of placing multistage-fractured horizontal producers in these areas. The paper deals with the redevelopment of the Cardium formation from a primary-recovery perspective only, with a focus on the fringe areas around the supergiant Pembina field, as well as the development of the largely untapped resource in the A Lobe of the Cardium in the Garrington/Caroline areas. Introduction The Cardium formation is regionally extensive, spanning an area of nearly 150 townships in central/southern Alberta. The formation has been described as a clastic wedge that prograded into the western interior seaway during Turonian-Coniacian time. Many sedimentological responses identified within the formation indicate that the sand accumulation took place in muddy and sandy inner- and outer-shelf, shoreface, lagoonal, tidal, estuarine, and coastal-plain settings. This wide variety of depositional environments resulted in a diversity of lithofacies, multiple disconformities, paraconformities, and diastems of varying lateral extents. The predominant rock types in the Cardium are mudstone and sandstone with small, but important, conglomerate fractions. The Cardium deposits formed a series of stratigraphic traps, the largest of which is the supergiant Pembina field in central Alberta. Cardium reservoirs and pools have been found at depths ranging between 1200 and 2800 m and typically contain light, sweet oil with varying amounts of dissolved gas. A number of rich-gas pools also can be found in the Cardium formation. Operators who target the Cardium formation frequently are the beneficiaries of excellent core data, as a result of the standard industry practice of the 1950s through the 1980s. In the broader Pembina area, the Cardium exhibits exceptional log resolution because of its relatively shallow depth of burial. Many of the logs in the Garrington/Caroline area are of an older vintage and of generally poorer resolution. The abundance of core-plug, well-log, and production-performance data from the more than 10,000 vertical wells that have targeted the Cardium allows for high-quality petrophysical analysis and detailed geological mapping. Some operators have begun to use 3D-seismic amplitudes and other geophysical attributes to study the reservoir quality and pore-fluid content in various portions of the Cardium.