Well Stimulation by Fracturing (Acid & Hydraulic) was quickly accepted by the Oil Industry since its introduction in the late 40's (first ever hydraulic Fracturing job was conducted in Kansas, U.S.A. in July, 1947), still, its applicability to Abu Dhabi fields and reservoirs did not gain momentum until the 80's. This late arrival can be attributed to the fact that poor Permeability Reservoirs were not considered for development before then, or because, even when the development of these "tight" Reservoirs was undertaken (as is true for the Upper Zakum), too many constraints were imposed (Geological, Reservoir and type of Completion). Such constraints made fracturing difficult to carry out.

Also, major advancement in Fracturing design and techniques took place in the 80's. Such techniques made it possible to reexamine the applicability of fracturing in the poor potential wells of the Upper Zakum.

This paper presents a review of the steps taken to ensure the success of Acid Fracturing in poor Permeability wells, and how constraints / limitations imposed by well completion and reservoir conditions were accounted for. . The exercise was successfully carried out in the multilayered heterogeneous reservoir of Thamama II in the Upper Zakum field, offshore Abu Dhabi.

The uniqueness of the exercise is that in all cases presented, Acid Fracturing treatment was conducted through one tubing string in dually completed wells, yet on rigless basis. Good post treatment productivity was achieved at optimum cost and therefore minimum pay back time.

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