Precise casing wear estimation is important to ensure appropriate well integrity and safer production of hydrocarbons. The amount of casing wear depends not only on operational parameters but also on the casing material. Experience from the Norwegian continental shelf (NCS) has proved that chrome material are subject to more wear as compared to carbon steel. 13% Cr materials are typically used where reservoir fluids are in contact with casing. However, some of the well construction techniques exposes 13% Cr materials to wear. In the NCS, multilateral wells where the contribution from each lateral is controlled, there is often a portion of 13% Cr material in the casing. Another frequently used technique involving wear of 13% Cr on the NCS wells is through tubing rotary drilling (TTRD).
The recent models for estimation of casing wear are valid for carbon steel but they fail to predict accurate wear for casings made of corrosion resistant alloy (CRA). Therefore, research was required to identify the reasons for the difference in wear characteristics of CRAs versus standard carbon steel.
A series of experiments were designed by analyzing data from NCS and tests were performed by varying the side force on 13Cr80 and 13CrS110 casings to investigate their wear characteristics. The experimental results revealed that wear estimation of chrome casings can be predicted. It was found that casings made from CRAs are subject to a different wear mechanism as compared to regular carbon steel. The research showed CRA material is prone to excessive wear depending on the side force. Furthermore, the contact pressure threshold for chrome casings has been established at low side force.