It is common practice to use steel casing when constructing and completing oil wells. However, well integrity issues caused by corrosion require well intervention operations which increase the non-productive time. This has led to investigations by researchers and engineers to improve the corrosion resistance of steel by modifying alloying elements. Some other researchers have suggested the use of aluminum alloy casing because of its resistance to corrosive H2S environments, and its lightweight characteristics. However, utilization of aluminum strings has not been reported in North Sea field applications. Although the durability of aluminum in corrosive environments is of interest, there are some other areas to be studied more in detail. These subjects include but are not limited to, mechanical properties of aluminum alloy, galvanic corrosion between the aluminum tubing and steel coupling, pipe wear, and interaction between cement and aluminum casing. Also the potential use of titanium casing elements can be of interest for selected applications. The primary goals of oil well cementing are achieving proper zonal isolation and anchoring the casing in the well. To evaluate these objectives, cement samples and casing alloys were tested in the lab prior to field operations. This lab testing includes measuring the hydraulic and shear bond strength between the cement and casing after the cement cures. In this study, shear bond strength and hydraulic bond strength between Portland cement and six different types of pipe were measured. The pipe samples tested were a titanium alloy and different aluminum alloys with coatings, and a steel pipe used as a reference. Three different Portland cements were used: two types of API Class G oil well cement and one rapid hardening cement. The obtained results showed that of these pipe systems, three showed a higher shear bond strength: titanium pipe, coated aluminum pipe, and steel pipe. Subsequently, these three pipes were used for measurements of hydraulic bond strength.

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.

Drill string vibrations are a significant concern during drilling operations, and are a common cause of downhole tool failures and decreases in drilling efficiency. Drill string vibrations are typically categorized in three ways: axial (the drill string is vibrating along the axis of drilling), lateral (the drill string is vibrating perpendicular to the axis of drilling), and torsional (the rotational speed of the drill string is varying along the axis of rotation). If applied correctly, the use of low elastic modulus and low density materials in a complex system will dampen vibrations. This hypothesis is confirmed through the use of multiple software simulations including an ABAQUS Finite Element Analysis (FEA) model and an MSC Adams multi-body dynamics model. The simulations pointed to the conclusion that including sections of aluminum drill pipe into the drill string will dampen drill string vibrations (Dziekonski, 2017). The low elastic modulus and density of aluminum reduce both the duration and severity of torsional vibrations in a stick slip type dysfunction. The reduction in severity of uncontrolled torsional oscillations will reduce the additional strain on threaded connections throughout the bottom hole assembly and drill string, as well as the impact caused by lateral vibrations, and the amplitude of axial vibrations. This overall reduction in vibrations can be used to increase the life of sensitive downhole components and increase the efficiency of drilling operations.

This paper is a retrospective of a recent project to design, manufacture and qualify a NACE MR0175 / ISO15156 compliant custom HPHT pressure vessel for the purpose of conducting accelerated corrosion testing for a major oilfield operating company. A conventional mechanical design processes begins with the sizing of the vessel via design calculations, and proceeds to creation of a series of design iterations before building the first prototype unit. This is followed by prototype testing required to validate design assumptions and safety margins. This commonly results in redesign and re-manufacturing of the components or the entire prototype unit in order to achieve the desired function and satisfy the safety criteria, leading to a long and expensive development cycle. Virtual prototyping migrates the early "design validation" phases from the physical realm to the computer thus making the ability to test design margins safer and easier, and providing a more comprehensive understanding of the assets capabilities. Computer aided design methods allowed for multiple virtual prototypes to be assessed, with the entire process from product launch to commercial delivery taking less than 8 months. Multiple design challenges were resolved by development of internal design practices following virtual prototyping approach. The approach was validated using laboratory tests and FEA modeling. Numerous procedures addressing design and product delivery challenges were developed: a methodology to follow ASME BPVC design rules for CRA based metallurgies not specified in the Code; a revision of an existing 10,000 psi metal-to-metal seal design to sustain test pressures and a technique for prevention of seal moment in a many-material system with different thermal expansion rates. In the end, using this virtual design approach, following a robust design code such as ASME BPVC Section VIII Division 2 enabled us to produce a first of its kind 30,000 psi / 650°F corrosion test vessel on a short delivery schedule that passed the 50,000 psi proof test required by our operator on its first try. Post-delivery operator requirement changes required a re-assessment of the vessel to a higher working pressure. This resulted in a new FEA analysis following the same logic as the original analysis, but benchmarked against the "as-build" material properties instead of the original material specifications. Post analysis; the vessel was physically validated by a hydro-test to 50,000 psi.