Method employing pressure transients in hydrocarbon recovery operations

A method in hydrocarbon recovery operations on a subterranean formation and comprising the application of at least one fluid into the formation, the method comprising:

• providing at least one partly enclosed space containing a fluid in fluid connection with the fluid in the formation,
• arranging a body in the partly enclosed space such that a first surface portion of the body is in contact with said fluid and a second surface portion of the body is free of contact with said fluid, the body hereby being positioned so as to separate the fluid filled part of said space from a part of said at least one partly enclosed space without fluid,
• arranging at least one object outside the fluid filled part of said space and outside said fluid, and
• inducing pressure transients in said fluid such as to propagate in said fluid and into the formation thereby enhancing a penetration rate of the fluid into the formation, where said pressure transients are induced by a collision process generated by the object falling onto and colliding with said second surface portion of the body such that the collision occurs outside said fluid filled part of said space and outside said fluid without the object making contact with the fluid,
• wherein said collision process is such that said body is moved about 1 mm or less by said collision process.