Rotary Sidewall Coring and Its Use in Real-Time Strength Estimation

Conventional coring and subsequent core testing are well known practices in civil, mining and petroleum industries. In the oil and gas industry, cores are tested in a laboratory and the information is used in drilling, evaluation, exploration, resource estimation and production processes. However, conventional continuous cores are costly, time consuming and often completely ignored for analyzing overburden, non-reservoir, or future reservoir sections. Rotary sidewall coring is a cost-effective alternative to continuous coring. It provides flexibility in picking selective depth intervals and in choosing key formation types. Unnecessary depth intervals can be skipped, enabling companies to avoid collecting ten to several hundred feet of continuous conventional coring after the coring begins. In the present work, large sets of sidewall cores were obtained from the BETA BHJ 12 well. The real-time data during the coring processes were analyzed for drilling time, rate-of-penetration and extent of core lengths obtained. This real-time information was explored to calibrate strength of rock types. Finally, the methodology was used to estimate the strength in real time