This paper was prepared for presentation at the 47th Annual Fall Meeting of the Society of Petroleum Engineers held in San Antonio, Tex., Oct. 8–11, 1972. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by who the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract The utility of aqueous foams as circulating fluids in wells with low bottomhole pressure has been established. Although foams are simple to prepare, their behavior to changes in flow and well parameters is complex. The effects parameters is complex. The effects on foam flow of a number of these parameters were investigated by parameters were investigated by using a computerized mathematical model developed from newly reported research. Trends in job design factors such as injection pressure, bottomhole pressure, pressure, bottomhole pressure, circulation time and lifting ability are shown to be related to flow velocity and the liquid volume fraction of foam. A series of figures, some operating rules and a table summarizing directional trends of these design factors for a number of the more important flow and well parameters are presented. It is concluded that foam job design studies should be done when new lob objectives, well configurations or fields are encountered. Introduction The effectiveness and economic attractiveness of aqueous foam as a circulating fluid in well cleanout and drilling operations has been shown. Foam is increasingly important for a wide variety of oil field work where its low density and relatively high solids-lifting capability are needed. Foam has been successfully used in conventional and thru-tubing operations both onshore and offshore, in hard rock and soft sand provinces, and in permafrost areas. A vast amount of permafrost areas. A vast amount of experience with this unusual fluid is now commercially available from a number of service companies who have completed approximately two thousand foam circulation jobs. Prediction of optimum gas and liquid rates, pressures, circulation time or solids-lifting ability is often difficult because of the complexity of foam circulation in wells.

The chemical process described here has proved to be an effective method of preventing fluid movement out of or into a wellbore. This process provides a strong, durable plug at normal formation temperatures as well as under steam injection conditions where most plugging methods fail. Introduction Control of fluid movement, from the wellbore into earthen formations or from the formation into the wellbore, is a universal problem in the oil industry. Injection profile control is an integral part of most assisted recovery or steam stimulation programs. Premature entry of water or gas into the producing Premature entry of water or gas into the producing wellbore in both primary and assisted recovery operations also creates many problems. Numerous mechanical, physical, and chemical techniques have been used to try to overcome these problems. The most commonly used technique is cement problems. The most commonly used technique is cement squeezing, a method that is much less effective than generally recognized. Cement, a particulate material that cannot penetrate formation matrix to any great depth, forms a filter cake on the formation face that often breaks down under pressure. Mechanical packers are used to isolate zones in a wellbore. packers are used to isolate zones in a wellbore. This technique is effective if the wellbore is cased and good cement bonding exists between the casing and formation. Lost circulation materials are often used to form a filter cake, which impedes fluid flow into thief zones; for the most part, noted improvements are temporary. A number of chemical processes for plugging or reducing formation permeability are commercially available. These processes range from pumping two chemical solutions into the formation to mix and form an insoluble precipitate to using relatively sophisticated polymer systems that are chemically activated prior to pumping into the matrix where they set up at a later time to form a gel or solid that plugs and reduces permeability. All are based on true solutions that can be pumped through matrix. The success of these techniques depends on the formation being treated (matrix or fracture plugging, carbonate content, etc.), volume of chemical used (large volume treatments are recommended with gel-forming systems to assure coverage), and the precautions taken to assure proper fluid placement. None of the commercial processes proper fluid placement. None of the commercial processes are recommended for steam injection wells. We have developed a chemical method for permanent formation plugging that has a number of permanent formation plugging that has a number of advantages over commercially available processes. In the following pages the process, process fluids, laboratory development, and field applications are summarized and discussed. Process Description Process Description This new process is based on the acid-catalyzed polymerization of furfuryl alcohol resins. It is polymerization of furfuryl alcohol resins. It is applied by injecting an acidic solution into the interval to be plugged, followed by the resin solution. The two solutions mix in the formation to start a rapid, vigorous, exothermic reaction forming a hard solid that fills the pore space (or fracture). JPT P. 559

the formation clay minerals helps determine when and where the chemical Hydroxy-aluminum chemical (OH-Al) miqht be used most effectively.has been used in hundreds of wells to Recoanizinq the effect of chemical sustain production by stabilizing incompatibility, temperature, and clays that cause permeability damage OH-A1 concentration on treatment and well sandinq.Commonly used in results is essential for optimum job conjunction with other well stimula-desiqn. tion processes OH-Al has prolonged the stimulated production response

Shaft and tunneling technology commonly employed in the mining and construction industries has hem shown to have application in the development of some petroleum deposits. The use of Shaft And Tunnel Access (SATAC) technology in the Athabasca Oil Sands in Alberta has been well documented by Haston, Best, and others. Arctic reservoirs, because of the hostile weather, are among the potential candidates for development using SATAC methods, particularly potential candidates for development using SATAC methods, particularly shallow (less than 5000') heavy oil reservoirs. Underground space concepts offer solutions to many problems now commonly associated with developing oil reserves in these and other areas. While not applicable to all reservoirs, SATAC is recognized technology and should be considered among the available tools to access and develop oil reservoirs. Possibilities include:employing mining to develop oil reserves;using for infrastructure, like access roads and pipelines; orusing in combination with other technologies like pipelines; orusing in combination with other technologies like subsea production. Introduction Archaeologists have documented man's use of underground space for shelter and protection. Natural caves were used first, but man soon began creating underground space as his needs for natural resources developed. European flint mines (13,000 BC), catacombs on Malta (3000 BC), the Sinai copper mines (3000 BC), and the Alps Hallstatt salt mine (2500 BC) cited by Willett are examples of man's early creation, as well as his use, of underground space. Abraham's well dug at Beersheba (1500 BC) is believed to be the earliest written record of man having sunk a well (shaft) to extract liquids from the earth for his use. Early oil production was developed through wells and underground openings dug by hand. Unocal's oil mine at Ventura (1884) still produces through drain holes drilled from a tunnel excavated using early mining methods and the first well in the Kern River (1899) Field was dug by hand. No industry has experienced more recent change than the mining and tunneling industry. Modern SATAC (Shaft And Tunnel Access) technology has made subterranean projects possible that were once only dreams in the minds of men. The Fixed Link (Chunnel) project between England and France is a reality. On October 30, 1990, a probe breakthrough between U.K. and French tunnel-boring machines under the English Channel achieved the realization of a 200-year old dream. Background It is not surprising that mining continues to be considered a technically viable method for developing some large oil deposits. Early petroleum developments used simple mining methods. The roots of petroleum engineering are in the mining and mechanical disciplines. Recent years have seen renewed interest in "oil mining" as conventional production continues to decline, costs of other enhanced oil recovery (EOR) methods increase, and environmental constraints grow. Industry publications, as well as daily news media, have discussed existing and planned "oil mining" projects. Most of these are mining projects only in the sense that tunnels or shafts are used to gain access projects only in the sense that tunnels or shafts are used to gain access to the oil reservoir through drain holes drilled into the reservoir from the tunnels and shafts. P. 567