Water weakening of chalk: A mechanistic study

PhD thesis in Petroleum engineering. At this point, only the introduction is available online, not the articles.Since the detection of the Ekofisk subsidence some 20 years ago, there has been a considerable research activity concerning chalk behaviour in general, and mechanical properties particularly. Due to the importance of water injection into chalk reservoirs to improve oil recovery, an extended experimental testing has been performed in order to further investigate the socalled water weakening effect. The mechanisms behind well instability, compaction, and subsidence experienced in the North Sea chalk reservoirs are, however, not completely understood