Increasing the Extraction of Oil by Water Flooding

Interest attaches to water flooding as a means of increasing the extractionof oil because of its remarkable success in the Bradford field in the northwestpart of Pennsylvania, and the possibility of application in otherlocalities. The constantly increasing demand for petroleum products and the increasingdifficulty of finding new oil fields is directing serious attention to the oilleft in the ground at the time when wells producing by normal methods haveapproached their economic limit. In Germany mining operations have proved thatproduction by wells over a period of 50 to 75 years has only recovered from 13to 15 per cent of the oil in the sand. In the Bradford field of Pennsylvania itis fairly well established that normal production over a period of 50 yearsrecovered only about 3000 bbl. an acre out of a total oil content of at least30,000 bbl. Similarly for many other fields it is estimated that recovery byusual methods runs from 10 to 40 per cent of the oil content of the sand. Inexceptional cases recovery may be higher, as in areas where edge waterencroaches rapidly or in open sands where gas pressure is unusually high andconserved by slow development. This unrecovered oil constitutes a tremendousreserve of petroleum in areas where conditions of drilling, sand, and water arewell known, and where the facilities for gathering and marketing the productionare already established. The means of recovering a portion of the oil remaining in old fields fallsinto three principal groups - mining, air flooding and water flooding. Miningis being successfully carried on in two fields in Germany, air flooding hasbeen found profitable in about 15 localities in the United States, and waterflooding is a proven success in the Bradford field of Pennsylvania and theBolivar field of New York. Only water flooding will be considered in this paperwhich is devoted primarily to what is actually being done in the Bradford fieldand the technique that surrounds it.