Abstract

With the increase in average lateral length for horizontal wells comes increased challenges for reaching total depth (TD) with the production casing. Any production interval left un-cased will not contribute to initial or ultimate production or be booked as reserves, which can have a major detrimental impact on the financials of these wells.

ALTISS Technologies has designed a patent pending aluminum casing concept to facilitate the installation of long cased laterals, and assist with landing casing at the total depth. Due to its low density and low modulus of elasticity, the aluminum casing is about half the buoyed weight and twice as flexible as comparable steel casing. These physical properties help the aluminum casing lighten the toe of the casing string and navigate through micro doglegs and tortuous wellbores.

The aluminum casing was designed with a focus on torque and drag reduction, to be used in limited quantities to maximize the benefits and ensure that casing reaches total depth. Analysis showed that 4,000 pounds of hook load could be added, without casing rotation, with as little as 160 feet of aluminum casing installed, in some cases. To ensure proper threaded connections with the low modulus aluminum, ALTISS designed its own 5 ½" premium threaded connection, which exceeded 56,000 ft.-lbs. yield torque in testing. Multiple aluminum tubular specimens were collapsed in a laboratory setting to validate equations which are not covered by API calculations, nor conventional closed form solutions (e.g. Timoshenko, Tamano). An experimental nano-coating is currently being evaluated that will protect the aluminum from potential forms of corrosion, including galvanic reactions and acid programs.

The advantages of installing aluminum casing may allow for eliminating expensive premium threaded connections needed for rotating casing, or alternatives such as floating casing. Ensuring the lateral is 100% cased improves initial production, allowable booked reserves, and ultimate hydrocarbon recovery of the well.

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