SynopsisFree-radical, graft polymerization of acrylamide onto lignin occurs in photolysed, distilled dioxane containing calcium chloride and trace quantities of ceric ion. The yield of the reaction is controlled by the amount of oxygen present during dioxane photolysis, the duration of photolysis, and the amount of calcium chloride in the reaction mixture. Polyacrylamide homopolymer is formed during the reaction and can be removed from the graft copolymer by base dialysis. Side chains of the reaction product can be hydrolyzed to partially hydrolyzed polyacrylamide by solution in aqueous base. Hydrolysis raises the limiting viscosity number of the product by a factor of up to 47. As a drilling mud additive, the ability of the reaction product to lower yield point, lower gel strength, or lower API filtrate volume increases with increasing degree of hydrolysis.

We gratefully note the support of the U.S. Department of Energy (No. DE-FG-22-82PC50799).

Partially hydrolyzed polyligning-(1-amidoethy-lene)) lowers yield point, polyligning-(1-amidoethy-lene)) lowers yield point, lowers gel strength, lowers API filtrate volume, and, after the mud has been hotrolled at 250 degrees F for 16 hours, functions more effectively as a thinner and agent to control filtration loss than does an equal concentration of chrome lignosulfonate in a water-base mud containing 28 ppb Wyoming bentonite. Poly(lignin-g-(1-amidoethylene) is formed along with poly(1-amidoethylene) in a graft copolymerization reaction of 2-propenamide on Kraft pine lignin contained in 1,4-dioxacyclohexane. Formation of graft copolymer was proved by attachment of a derivitized 1-amidoethylene sidechain to lignin and demonstration by U.V. spectroscopy that sidechain and backbone migrate together in a size exclusion column. The dried, two-part reaction product is treated with aqueous base to form anionic polymers which produce the changes in mud rheology noted above. Both produce the changes in mud rheology noted above. Both components of the reaction product are active in controlling mud properties. Introduction Since the introduction of calcium lignosulfonate deflocculants in 1947 and chrome lignosulfonate modifiers in 1955, lignosulfonates have been used extensively in drilling mud formulations. Over 34,000 metric tons of lignosulfonates are used in the drilling industry annually. Problems in both the supply of lignosulfonates and in their application may ultimately remove these chemicals from muds, however. Supply problems result from the slow switch in paper problems result from the slow switch in paper production from the sulfite process, which produces production from the sulfite process, which produces lignosulfonates as a byproduct, to the Kraft process, which produces lignin as a byproduct. This reduction in produces lignin as a byproduct. This reduction in the available supply of lignosulfonates is caused by process economics and environmental considerations. process economics and environmental considerations. The switch by paper manufacturers to the Kraft process may be reversed sometime in the future, but there is no current indication that the forces causing this change will abate. Technical problems in the application of lignosulfonates are 1) thermal decomposition above 121 degrees C 2) causing corrosion from decomposing residues in high temperature wells, and 3) significant reduction in additive effectiveness as bottom hole temperature approaches 205 degrees C. Other materials which could replace lignosulfonates must possess 1) low cost, 2) availability, and 3) comparable or improved performance. One candidate to replace lignosulfonates is lignin, a scrap material being produced in larger amounts each year but currently little used in drilling. In order to apply lignin to well drilling problems, it must be chemically treated to increase its solubility, enhance its thermal stability, promote metal ion complexation, and make it an effective deflocculating agent. In an effort to produce such a lignin derivative, Kraft pine lignin produced by the West Virginia Pulp and Paper Company under the trade name Indulin AT has been graft copolymerized* with 2-propenamide (acrylamide) to make poly(lignin-g-(1-amidoethylene). In the following sections, the synthesis procedure for making or hydrolyzing copolymer drilling procedure for making or hydrolyzing copolymer drilling mud additives, proof that product is copolymer, physical properties of the product, methods for physical properties of the product, methods for forumulating mud with derivatives of additive, the results of tests on mud containing additive, and interpretation of those results will be presented. *Graft copolymerization is the process of adding a polymeric sidechain [poly(1-amidoethylene)] to an polymeric sidechain [poly(1-amidoethylene)] to an existing polymer (lignin) to produce a two-part molecule. The two parts of the molecule are of different chemical composition or structure. In this case, the graft copolymer formed, trivially named ligninacrylamide graft copolymer, PLA, can be treated with base to form poly(lignin-g-[ (1-amidoethylene)-Co-(sodium 1-carboxylatoethyelen)]) [partially hydrolyzed lignin-acrylamide graft copolymer, PHLA] and the two compounds have been tested as drilling PHLA] and the two compounds have been tested as drilling mud additives. p. 97

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