| Popis: |
Published in Petroleum Transactions, AIME, Volume 204, 1955, pages 79–85. Abstract In predicting the sweepout pattern efficiency to be expected in a secondary recovery operation, the reservoir engineer is often confronted with a situation in which part of the producing formation lies between the last row of wells and the reservoir boundary. To date, there has been little or no reference in the literature to sweepout pattern efficiencies in such areas. This paper presents the results of a laboratory study in which the area contacted around the edge of a reservoir injected in a five-spot pattern was determined. The X-ray shadowgraph technique was used in this study. It was found that surprisingly large portions of the reservoir area lying outside the well network are contacted by the injected fluid before abandonment conditions are reached. In fact, it can be said that at least 90 per cent of the area lying outside the last row of wells and within a distance of one well spacing of these wells will ultimately be contacted by the injected fluid in the case of most water floods. From the results given in this paper, it is possible to estimate not only the extent to which encroachment into these areas will occur but also the injection volume necessary to produce the wells to abandonment conditions. Introduction While considerable work has been done in recent years evaluating the fraction of the reservoir contacted as a function of the mobility ratio for several different well patterns, there has been practically no mention of what happens to the oil in that portion of the reservoir which lies between the last row of wells and the reservoir boundary. In fact, the assumption is generally made that little or no recovery can be expected from this area. |
