Sucker Rod Wear In Directionally Drilled Steamflood Wells

Abstract

Abstract Husky Oil's Thermal Operations District in the Lloydminster, Saskatchewan area, has had extensive experience with sucker rod wear in directionally drilled steamflood wells. Husky's two major steamflood projects, the Aberfeldy Steamflood Pilot (steam drive) and the Pikes Peak Pilot (cyclic with some post-cyclic stream drive), have drilled and produced directional wells from pads since 1983. As expected, the frequency of wear-related sucker rod failures in directionally drilled wells is much higher than in conventional vertical wells. Through careful data gathering and analyses, Husky has attempted to quantify the degree of incremental wear as well as identify the controlling mechanism(s) (i.e. maximum dog-leg, maximum hole angle, etc.). Rod wear-related problems are described in depth. The frequency and location in the rod string of the wear-related failures are compared with a number of parameters to determine the major factors contributing to rod wear. The various methods and items tested by Husky to reduce and control rod wear are described and discussed. A summary of conclusions based on the data as well as a suggested rod/tubing maintenance program are included in this paper. Introduction Husky Oil Operations Ltd. has been active in the Lloydminster, Saskatchewan / Alberta, heavy oil fields since 1946 and currently operates over 2000 producing wells and five active enhanced oil recovery (EOR) pilots. The Lloydminster operators produce from a series of lower Cretaceous sands at depths between 400 m and 600 m. The sands are reasonably clean, moderately sorted, and poorly consolidated. Porosity can vary between 25% and 35%. Permeability ranges from 0.5 darcies to 8 darcies. The oil produced in the area is dense and viscous. Density is generally between 911 kg/m3 and 980 kg/m3. Viscosity can be as high as 131 Pa •s. The original-oil-in-place in the Lloydminster area has been estimated at 500 million m3(1). Probably less than 10% is recoverable by conventional means, EOR recoveries have been estimated at 25%. Pad Well Completions Husky began drilling EOR wells from pads in 1983. The advantages of pad drilling are well documented and accepted by the operating companies in the area. The close spacing used in the EOR pilots (as low as 1 ha), the reduced cost of fluid injection and production lines, the centralization of facilities, and the large reduction in surface area requirements make pad drilling of EOR wells especially attractive. Husky currently has over 100 pad wells in its EOR pilots. Pad sizes vary between 3 and 14 wells. The wells are typically equipped with 178 mm casing, 89 mm EUE tubing, 22 mm grade C sucker rods, and 64 mm rod (insert) pumps. When the first pad wells were brought on stream in 1983 (at the Pikes Peak Cyclic Steam Pilot), the field personnel were expecting to have significant rod wear problems. The frequency of rod wear-related servicing was higher for the new wells but not alarmingly so. The installation of rod rotators and the implementation of a rod maintenance program kept the problem under control.