SOME CONCEPTS ON FORMATION PROTECTION AND THE RELATED TECHNOLOGIES

This paper points out that the traditional concept on formation damage, that the reservoir is "killed" by drilling fluid of high density is false and lack of scientific foundation. A large amount of laboratory and field tests show that there are 2 major causes of formation damage. One is the great differential between higher hydraulic pressure in the well and the lower formation pressure; the other is the incompatibility between drilling fluid type and formation rock. The causes are further studied from the theoretical and practical aspects, and the related technologies for formation protection are also described.