Integrated Casing Wear Management in Well Design and Drilling Operations with a Field Case Analysis

Abstract Casing wear is an ongoing concern for well integrity especially in deep wells. Severe casing wear especially on the production casing, which normally serve as secondary barrier of a well, can result in downgrading the pressure capability, significant remedy costs, or even the loss of a well. The casing wear shall be managed from both design and operational phases to ensure well integrity not affected by casing wear. Casing wear is the mechanical work of friction between the contacting areas of drill string and inner wall of casing. There are different casing wear mechanism and wear patterns because of the movement of drill string. An industry standard casing wear model was used to compute crescent-shaped casing wear. The three major inputs for the model are: side force at drill string and casing contacting aera, wear factor and total string rotating revs. Compound casing wear also discussed for the mechanism and contributing factors. Practices both in well design phase and drilling phase are summarized in paper. Side force shall be checked in well design phase with planned dog-leg severity, expected hook load and wear factor. Excessive side force should be avoided from well design phase to reduce the risk of severe casing wear. In drilling phase, the actual wellbore tortuosity and max dog-leg severity need to be monitored and managed to below threshold defined in well plan. Operationally, the ditch magnet metal weight shall be recorded on daily basis with monitoring against krevs, time and distance drilled, and the drill string tool joint hard-banding worn status also shall be recorded for the depth and worn severity. Those data points will be analyzed to build relations with daily string revs and footage drilled. A representative field case is used to verify the casing wear modeling validity and effectiveness of casing wear management practices. The casing wear modelling outcome identically matches the peak sections from the ultrasonic (USIT) casing wear logging results. The high side force interval depths recorded high casing wear. The drill pipe tool joint hard-banding wear section also matches the high side force intervals in top hole. This paper should provide help on casing wear prediction and mitigation. The paper verified the casing wear model and provided wear factor reference for a certain drill string, mud property and casing grade. Some recommendations are proposed for casing wear mitigation.