Chemical Methods for Shutting Off Water in Oil and Gas Wells

Abstract

The fact that intrusion of water into oil wells can be prevented by treatingthe sand adjacent to the well seems to have been only recently recognized. Swan1 mentions the process of solidifying naphthalene in strata. R. Van A. Millsrecommends the use of materials such as sodium silicate and sodium carbonate, which react with oil-field water to form solid plugging agents.When a well is drilled in a new field the oil sands are found essentiallydevoid of water (Fig. 1). Unless a completely impermeable break exists over wide areas in the field, no water is found above the lower limit of theoil zone and no oil is found below the upper limit of the water zone. Afterconsiderable oil has been taken from the well, however, it is almost universalexperience that water intrusion occurs. This intrusion may be of two kinds. Thewater may follow a path parallel to the bedding planes of the producingformation through loose streaks in the pay sand, as shown in Fig. 2, or thewater level of the field may rise and enter the well by coning (Fig. 3). Waterentering from the side is called "edge water," and that coming in fromthe bottom is called "bottom water."