State Of The Art Of Water Coning Modelling And Operation

SPE 13744

SPE

STATE-OF-THE-ART F WATER CONINGMODELLING O AND OPERATION

by Abbas A. Alikhan, Kuwait Univeralty, Kuwait; and S.M. Farouq ALi, University of Alberta, Bdmonton, Caneda

This paper was presented at the 4th Middle Seat Oil Show Society of Petroleum Engineers of AIME held in Bahrain, March 11-14, 1985. The material is subject to ccmraztim! by the Suthor. ?eP-iSSiQn J c~p; Larestricted to an abstract of not more than 300 words. Write: P.O. Box 833836, Richardson, Texas, U.S.A. 75083. c Copyright 1977, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. ABSTSACT Water-coning ia often a serious operational problem in oil formations with underlying water. In the Middle East, some of the largeat oil reservoirs have water-coning probl~a. The operationof a field under water-coning can employ a number of strategies, ranging from production limitation to production at maximum rate, possibly with interval control. This paper reviews the state-of-the-art of water-coning from the point of view of field operation, experimental modelling and numerical simulation. Selected field examplea are cited. It is ahown that water-coning control measures are oflimited efficacy at best, under practical conditions. Other techniques, such aa barriera, are of academic interest only. Production at very high rates - with concomitant high water production ratea - can be problematic in the Middle Eeat reservoira, with very highly saline connate wsser. mobility ratio, total production rate, vertical permeability, and oil zone thickness. The coning problem maybe delayed in some of the large oil reservoirs in the Middle East, where a tar barrier (“tar mat”) is Present between the oil and the Vatg!rZones. *“ t~= ~Ch=Z ha~$, =G~b,a bg~~ier alSO impedes the water drive. This papers attempts to bring together much of the knowledge on water coning - theoretical, experimental, and numerical simulation studies, with reference to field ~perience whereapplicable. MSCNANICS

“Water coning” refers to the configuration of the oil-water interface, where a thick oil layer Is underlain by a water-saturated layer, and the oil zone Is partially penetrated by a well (Fig, 1), Aa oil production proceeds, the induced potential gradienta cauee the oil-water contact to rise upward, Simulation of water-coning and/or gas coning with the water wentually breakingthrough the oil is possible on a single well basia. However, it ia Into the well. Subsequently, water production still not practical to simulate water-coning on a increeeea rapidly, with the oil cut decreaa%ng Ca a field=’it!e basis. TFiieumericai ciifficuities n involved few percent, or even leaa. Over a sufficiently long and some of the solutions proposed are diacuaaed. production period, the oil cuttenda to stabilize, if the boundary conditions r-in unchanged. The Experimental rnodell@ Qf ESt=X-CCSi:g has =ater coning probim ia thus highly complex, and an been fairly auccesaful, again on a single well basis. I analytical solution la mot possible. The probkm, &~eaio-d~uj, ‘~erieai @*iation “naaprwided ueeaa described, can be solved numerically, at leaat ful backup to physical modelling.Types of experifor a single well. Fieldwide water coning problem mental models used are reviewed. haa been tackled in some caaea, but ite satisfactory aolutlon would require the next generation of computers. On the whole, tha paper provides a useful view of all aspects of water-coning, and should be of ANALYTICAL SOLUTION value to large segment of petroleum engineera and reaeerchers. Many authors haveoffered aolutiona for the steady state water coningigaa coning problem. (Gas INTRODUCTION coning ia similar to water coning, except that the cone is inverted). The first of these is due to Water coning is a serious problem in many Musket (48), published in 1935. Musket’a treatment, ollfielda. where tb~ Qfi ZQD= h~g : g:te: ~=~: ~=ie-W. @iialso those of many others after him, is baaed It,...