There is high demand for water shutoff in quite a few SAS completed horizontal wells in the Bohai Bay, China. The popular swellable packer in combination with the ICD screen method cannot be adopted because segmentation cannot be achieved in the annulus between the SAS and the borehole wall by the swellable packers for the SAS is unable to be tripped out. A conformance control method is introduced and a case study is provided.
When the SAS string is not tripped out, first the path for the particles to flow through is established by perforation. Then, a string of ICD screen with smaller diameter is run in place, followed by the pumping of the continuous pack-off particles into the annulus (the inner annulus) between the ICD screen and the SAS. Meanwhile, the particles being carried by the fluids also pack the annulus (the outer annulus) between the SAS and the borehole wall through the penetrations on the SAS. Thus, the function of axial channeling prevention is realized by the rings of particles.
The well in the case study is an old well that suffered from high water cut, sand production and mud clogging simultaneously. For this operation, the filling rate of the particles was 104.2%, indicating the particles were tightly packed in the inner and outer annuluses and segmentation in the production interval was realized. After commissioning, the water rate dropped from the original 638m3/d to 85m3/d. The oil rate resumed to the level before the well was shut in and later slowly increased to 40.3m3/d. Water shutoff and oil enhancement was realized and neither sand production nor mud clogging occurred. Three functions are realized via the adoption of this method. Firstly, water shutoff and oil enhancement are realized via conformance control; secondly, both rings of particles together with the filtering layers in jacket provide better sand control; thirdly, the rings formed by the tightly packed particles are capable of preventing mud clogging.
In this paper, perforation is innovatively proposed to establish the path for the particles to flow through so that both annuluses are tightly filled by particles, together with the ICD screens, conformance control is realized along the entire production interval and the target of water shutoff and oil enhancement is achieved. Accordingly, high CAPEX for sidetracking is avoided and the single well ROI is improved.