A non-destructive method for mapping formation damage

Applicability of an ultrasonic method for non-destructive mapping of format ion damage is reported for the first time. Oil-saturated and 'mud'-damaged Berea rock samples were prepared in the laboratory using a leak-off apparat us and machined dry rocks. The depth of 'mud invasion' was monitored under varying conditions of overbalanced pressure DeltaP and contamination time D eltaT. An interesting observation is that a region of DeltaP similar to 2.0 7 x 10(3) kPa produces minimum invasion depth under the conditions investig ated. The results are discussed in the context of horizontal wells. (C) 200 1 Elsevier Science B.V. All rights reserved.