DETERMINATION OF CASING WEAR FACTOR FOR PROPOSED NEW WELLS USING SIMULATION BACK MODELING

Abstract

As shallow and easily accessible oil and gas reservoirs are becoming depleted, so oil and gas industry turned its interest towards deeper and complex reservoirs. Traditional drilling methods have been less convenient for deep drilling challenges. More complex well paths and tough drilling conditions have pushed drilling technology off limits. Deep wells needs longer drill strings and large number of rotating hours, which have been found to wear out casing pipes that supports the walls of the well at dangerous rates. The use of top drive systems and the ability to back ream while rotating is now common practice, which exaggerate the problem.

Casing wear can become a critical problem threatening well safety and permanence. It can cause the abandonment of a well before reaching total depth or, in certain cases; it can lead to blowouts, lost production, and other hazardous and expensive problems.

For many years, the measure taken to deal with wear problem was the application for wear resistant materials on the drill pipes tool joints. These wear resistant materials are commonly referred to as hard-banding materials. The hard-banding materials successfully protected the drill pipes from wear but, they have been found causing rapid sever wear to the casing inner surface which increased the problem. Operators start recognizing the operational threat to the integrity of their wells and the associated economic and environmental impact, so they have start-studying casing wear issues. Pre determined laboratory wear factors have shown to correlate poorly with actual wear seen in the wells after it has been drilled.

Therefore, our study will focus on how to find a method to determine a proper wear factor from real wells that already have been drilled, by simulating casing wear based on drilling data from field and thereby back calculate the wear factor by adjusting the software wear prediction graph to fit with actual wear graph. Comparing the simulated software wear graph with actual wear graph, will produce two wear factors the average wear factor and the maximum wear factor. Study will focuses on maximum wear factor, which recommended for use in the casing design phase.

Our results shows that L80-13cr casing has much less wear resistance than P-110 casing, and wear factors are dependent upon individual wells and its wear peaks. Casing wear peaks may be unpredictable at the planning phase, which make casing wear accurate prediction very difficult process.