Bond Strength Between Different Casing Materials and Cement

Abstract

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.

Experimental Study of Hydraulic Sealability and Shear Bond Strength of Cementitious Barrier Materials

“…The shear bond strength of class G cement at the pipe interface was only 17% of the bond strength with the bar. In another study with the same cement and similar grade of steel bar in the middle, Khalifeh et al [14] reported the shear bond strength of 1.3 MPa, which is 58% lower than the current measured strength. Following sample preparation procedure but increasing temperature by 20°C and curing under elevated pressure of 3.4 MPa has positively impact shear bond strength.…”

“…The compatibility of the casing material and the cementitious slurry is a necessity. In an earlier experimental study conducted by Khalifeh et al [14], incompatibility of aluminum pipe and the API neat class G cement was highlighted. Steel pipes are common materials for casing the borehole.…”

“…In another experimental study, Khalifeh et al [14] investigated the bond strength of Portland cement with six different pipe materials, including steel (reference material), titanium, two different grades of uncoated aluminum, and two different types of nanocoated aluminum pipes. They prepared the test specimens by curing cement around 50 mm pipes at an elevated temperature of 70°C and atmospheric pressure for 7 days.…”

“…Several experimental studies investigated hydraulic bond strength of cement-casing or cement-formation interface at both small-and large-scale [10,14,20]. The experiments were conducted by continuous injection of gas or liquid at the interfaces, and the pressure development and/or the flowrate during the test were monitored.…”

Specification for Permanent Plugging Materials

“…Hydraulic bond strength failure may eventuate from shrinkage or expansion of plugging material or expansion of casing caused by reservoir pressure build-up and/or due to interaction in the interface of casing and plugging material [14].…”