Issues and Techniques of Plugging and Abandonment of Oil and Gas Wells

Abstract

Abstract In the oil industry today there are over 600,000 producing wells, all of which will be plugged at some time in the future. Annually, approximately one-third of all oil and gas wells drilled are dry and require plugging in the abandonment process. Unless required by law, most abandonment plugs are not checked for their location and are assumed to have been properly placed. Thirty-four of the 50 states in the US have plugging rules governing the techniques for plugging and abandonment of various wells. Written over a long period of time and by varying regulatory agencies, wide variations exist in these rules. Outside the oil and gas industry, wells are drilled for industrial, disposal, and seismic purposes, freshwater production, and solution mining. All of these wells may have differing or nonexistent abandonment rules. Some states require strict procedures for abandonment of oil and gas wells, but have few or no regulations or requirements for other wells, even though these wells encounter the same freshwater formations. This paper reviews the latest recognized techniques for plugging and abandonment, and highlights the states having the most desirable rules for plugging to preserve freshwater horizons. The paper highlights poor techniques and practices used for plugging holes, and discusses troublesome areas such as wells that are not properly plugged and abandoned. The paper presents the issues of plugging and abandonment of wells including materials, techniques, plug testing, and regulatory requirements. Introduction Holes or wells have been dug or drilled for various purposes in all areas of the US since it was founded. The earliest of these wells was probably in search of fresh water as settlers moved across the US. Since these early dates, holes have been drilled for the following purposes:industrial and municipal applicationsdisposaloil and gasmine drainagetestingseismic purposessolution miningmeasurement of physical properties of downhole formations P. 507^