United States Patent (19. 11) 4,059,533 Watson et al. 45 Nov. 22, 1977 (54) OXYGENSCAVENGING METHODS AND 3,399,725 9/1968 Pye ....................................... 166/275 ADDITIVES 3,852,201 12/1974 Jackson ................................. 252/8.5 (75 Inventors: Jimmie L. Watson; Leroy L. Carney, FOREIGN PATENT DOCUMENTS both of Duncan, Okla. 6,414,645 6/1965 Netherlands .......................... 252/8.5 (73) Assignee: Halliburton Company, Duncan, Okla. OTHER PUBLICATIONS (21) Appl. No.: 518,306 The Merck Index, Eighth Edition, Published 1968 by 22 Filed: Oct. 29, 1974 - Merck and Co., Inc., pp. 958 and 960. 51) Int. Cl.2 ....... e o os see s see a woo C09K 7/02; C09K 7/04; Primary Examiner-Herbert B. Guynn E21B 43/22; CO1B 17/66 Attorney, Agent, or Firm-Robert S. Nisbett; Thomas R. 52 U.S. C. ................................... 252/8.5A; 175/64; Weaver; John H. Tregoning 252/8.5 B; 252/8.55 B; 252/188 58) Field of Search .............. 252/8.5 A, 8.5 B, 8.5 C, 57 ABSTRACT 252/8.55 D, 188; 166/279, 310, 175/64; This invention relates to methods and additives for 423/515, 512 R, 265 scavenging oxygen dissolved and entrained in liquids (56) References Cited which are particularly suitable for removing dissolved and entrained oxygen from polymer-containing fluids U.S. PATENT DOCUMENTS used in drilling and completing well bores as well as 1,810,663 6/1931 Kritchevsky et al................ 252/188 water flood and other procedures carried out in the oil 1,810,665 6/1931 Kritchevsky et al. ... ... 252/188 field. The oxygen scavenger additive is sodium dithio 2,702,789 2/1955 Teichmann et al. ..... ... 252/8.5 nite or a mixture thereof with sodium dithionate dis 2,718,497 9/1955 Oldham et al. .. 252/8.5 3,017,351 1/1962 Scott et al. ... 252/8.5. persed in a liquid carrier such as a hydrocarbon. 3,301,323 1/1967 Parsons .............................. 175/64 X 3,343,601 9/1967 Pye .................................. 166/275 X 5 Claims, No Drawings 4,059,533 1. 2 bentonite cakes out on the walls and the well bore OXYGENSCAVENGING METHODS AND thereby reducing fluid loss. ADDITIVES The potassium chloride component utilized in aque ous polymer drilling fluids functions to prevent the The presence of dissolved and entrained oxygen in cuttings produced by the drill bit from swelling and liquids utilized in industry is often detrimental in that being dispersed throughout the drilling fluid. This al the oxygen reacts with the exposed surfaces of equip lows the cuttings to be readily screened out of the dril ment contacted by the liquids or reacts with other com ling fluid using conventional surface equipment and the ponents contained in the liquids which in turn react solids content of the drilling fluid to be maintained at a with the surfaces causing corrosion and the deteriora 10 desired low level. tion thereof. As stated above, oxygen scavengers used heretofore A particular problem of this type is encountered in are relatively ineffectual when used in polymer drilling the drilling and completing of well bores penetrating fluids. This is primarily due to the oxygen reactive com subterranean oil and/or gas producing formations. That ponent of the scavenger preferentially reacting directly is, drilling fluids circulated through the drill string and 15 with the substitutable carboxyl groups of the polymer drill bit into the well bore often contain dissolved and or the catalysts incorporated in the scavenger reacting entrained air which enters the drilling fluid as it is circu therewith. lated through surface separating and screening equip By the present invention methods and compositions ment, mud pits, etc. The presence of oxygen from the for scavenging oxygen from liquids are provided which air in the drilling fluids drastically increases the rate of 20 are particularly suitable for use in aqueous polymer type corrosion and deterioration of metal surfaces in the drill non-dispersed drilling fluids and other polymer fluids string, casing and associated equipment as compared to utilized in well bore drilling and completing proce drilling fluids which do not contain oxygen. The use of dures. polymers in drilling fluids greatly increases the amount The oxygen scavenger additive of the present inven of entrained oxygen which is carried downhole during 25 tion is comprised of an oxygen reactive material se circulation. - lected from the group of sodium dithionite, and mix While a variety of oxygen scavenger additives have tures thereof with sodium dithionate. These materials been developed and used successfully with conven selectively react with dissolved oxygen in liquids in tional drilling fluids containing dispersed solids, e.g., cluding those containing polymers having substitutable 30 carboxyl groups therein. While the sodium dithionite or sodium sulfite catalyzed with a transition metal, hydra mixtures thereof with sodium dithionate can be added zine, sulfur dioxide dissolved in a carrier liquid and directly to the liquid from which oxygen is to be scav others, these heretofore used oxygen scavenger addi enged, such materials are difficult to handle and present tives are relatively ineffective for removing dissolved a fire hazard when exposed to the atmosphere. and entrained oxygen from polymer type non-dispersed 35 In accordance with the present invention an oxygen solids drilling fluids. scavenging additive is provided containing sodium di Aqueous polymer type drilling fluids have recently thionite or mixtures thereof with . sodium dithionate been developed and have several distinct advantages suspended in a liquid carrier having the property of over conventional drilling fluids containing high solids insulating the oxygen reactive materials from the atmo dispersed with agents such as lignosulfonates. That is, sphere. The resulting additives can be safely handled aqueous drilling fluids containing a polymer component and conveniently added to liquids from which oxygen is as a viscosifier, a polymer fluid loss component and a to be scavenged. potassium chloride component, referred to generally as While a variety of carrier liquids can be utilized in the low solids non-dispersed drilling fluids, are advanta oxygen scavenging additive of the present invention, geous in that less viscosifier and filter loss component is 45 liquid aliphatic hydrocarbons, liquid aromatic hydro required than in high solids fluids and the cuttings pro carbons, and mixtures thereof are preferred. The most duced in the drilling operation do not disperse in the preferred liquid carrier is diesel oil. drilling fluid making it possible to readily screen out The oxygen reactive materials are preferably added such cuttings using surface screening equipment and to to the carrier liquid in an amount of from about 40 keep the solids content of the drilling fluid low. A low 50 percent by weight to about 60 percent by weight. How solids content in the drilling fluid is advantageous be ever, as will be understood, the oxygen reactive materi cause less solids from the drilling fluid are placed be als can be combined with the carrier liquid in any con tween the drill bit and the earth formation being drilled, venient amount so long as the carrier liquid retains its increasing the penetration rate. ability to insulate the reactive materials when the addi The polymer component used in polymer non-dis 55 tive is exposed to the atmosphere. persed drilling fluids generally is comprised of a poly The reactive materials can be dispersed in the carrier mer or copolymer having one or more substitutable liquid in any convenient manner, preferably by sparging carboxyl groups therein. Examples of such polymers the reactive materials into the carrier liquid beneath the are hydroxyethylcellulose, carboxymethyl hydroxyeth surface thereof to avoid contact with air. In order to ylcellulose, copolymers of vinyl acetate and maleic maintain a dispersion of the reactive materials in the anhydride, polyacrylate, polyacrylamide, and mixtures carrier liquid, thickening agents such as oleophillic clay, thereof. The addition of these polymers to an aqueous fused silica or dimerized saturated and unsaturated fatty fluid provides viscosity and thixotropic properties acids can be added to the slurry. Preferably, fused silica thereto as well as friction loss characteristics. is utilized as the thickening agent for the additive and is The viscosifier and fluid loss component generally 65 added thereto in an amount of about 1 percent by used is Wyoming bentonite (sodium montmorillonite) weight of the slurry. which when placed in the aqueous fluid hydrates and A particularly preferred oxygen scavenger additive swells, adding viscosity to the fluid. In addition, the of the present invention is comprised of diesel oil pre 4,059,533 3 4. sent in an amount of about 53 percent by weight, a tiary oil and gas recovery operations as well as in other mixture of sodium dithionite and sodium dithionate oil, gas and water well completion and production tech present in an amount of about 46 percent by weight and niques. Moreover, the additives of the present invention fused silica present in an amount of about 1 percent by have a universal application for scavenging oxygen weight. The resulting additive can be safely handled from liquids and thereby preventing corrosion and and exposed to the atmosphere for periods of time with chemical deterioration of surfaces contacted by the out adverse results. In addition, the additive is pourable liquids. The additives are effective for the removal of so that it can be immediately and conveniently com oxygen at small concentrations and do not require cata bined with the liquid from which oxygen is to be scav lysts or other ingredients for accelerating the oxygen enged. 10 reaction. While the oxygen scavenger additive of the present In order to further illustrate the methods and addi invention can be utilized for scavenging oxygen from tives of the present invention, the following examples aqueous, hydrocarbon and other liquids, it finds particu are given: lar utility as an oxygen scavenger for polymer fluids and drilling fluids used in drilling and completing well bores 15 EXAMPLE 1.