Controlling salt contaminated drilling fluids with ethylene dicarboxylic acid
United States Patent 11 1 Walker 1 CONTROLLING SALT CONTAMINATED DRILLING FLUIDS WITH ETI-IYLENE DICARBOXYLIC ACID [75] Inventor: Thad 0. Walker, Houston. Tex,  
 [73] Assignee: Texaco Inc., New York, NY.  
 {22] Filed: Jan. 2, I973 [21] Appl. No.: 320,032  
 [52] US. Cl 252/85 C; 252/85 R; 252/85 A [51] Int. Cl. E2&#34;) 2l/04 [58] Field of Search 252/85 R, 8.5 A, 8.5 C  
 [56] References Cited UNITED STATES PATENTS 2,911,366 11/1959 Hcdrick et al 252/85 A 2,948,678 8/1960 Turner et al................,..252/8.5 A 3,070,543 12/1962 Scott 252/85 A 3,070,544 12/1962 Johnson et al 25218.5 A  
 [451 Apr. 22, 1975 3,216,934 ll/l965 Reinhard 252/85 A 3.222.278 12/1965 Harryman et al..... 252/85 A 3.654.164 4/1972 Sperry 25218.5 A  
 Primary E.\aminerBenjamin R. Padgett Assistant ExuminerB. Hunt Attorney, Agent, or Firm-Thomas H. Whaley; Carl G. Ries [57] ABSTRACT 10 Claims, No Drawings CONTROLLING SALT CONTAMINATED DRILLING FLUIDS WITH ETHYLENE DICARBOXYLIC ACID This invention relates to a fresh water drilling fluid for drilling wells through subsurface formations by means of well drilling tools. and particularly to a drilling fluid that has been contaminated with salt in the formation. with the result that its physical properties have been substantially impaired. The invention is also concerned with a method of drilling wells employing the fresh water drilling fluid as well as an additive for the contaminated drilling fluid.  
  Drilling fluids. or muds as they are sometimes called. are slurries of clayey solids used in the drilling of wells for tapping underground collections of oil, gas. brine or water. Such fluids have a number of different functions. the most important of which are to assist in the removal of cuttings from the well. to seal off formations of gas, oil or water which may be encountered at different levels. to lubricate the drilling tool and drill pipe which carries the tool. and to hold the cuttings in suspension in the event of shutdowns in drilling.  
  An ideal drilling fluid is a thixotropic colloidal system. i.e.. a fluid which on agitation or circulation (as by pumping or otherwise) has a measurable relatively low viscosity and is free-flowing (not plastic). particularly at high temperatures. but when such agitation or circulation is halted. the fluid sets or gels. The rate of gel formation is such as to permit the cuttings to fall only a short distance before the gel structure is sufficiently strong to support them.  
  When such a drilling fluid having the proper viscosity. the proper gel rate and proper gel strength is circulated through a well bore. it has a sufficiently high viscosity to carry the cuttings and sand from the bottom of the hole to the surface and it has a gel rate such as to allow the cuttings and sand to settle in a settling pit. On standing in a quiescent state. it develops sufficient gel strength to prevent the settling ofthe cuttings. sand or weighting material. etc., in the well bore when it becomes necessary to discontinue circulation for any appreciable period of time. Such a fluid is also characterized by its ability to form a mud cake on the borehole wall. thereby assisting in sealing off the traversed formations and inhibiting so-called water loss. i.e.. loss of water from the drilling fluid.  
  One of the principal problems in mud chemistry is the production of suitable fresh water drilling fluids having satisfactory dispersibility. and the necessary thixotropic properties discussed above. when substantial amounts ofsalt are met in the formation during drilling operations. ln such instances the drilling fluid properties are materially changes and the drilling operation is interrupted to meet this situation.  
  One known method to control the resulting adverse properties ofthe drilling fluid contaminated with salt is to thin the mud by water dilution. This method is disadvantageous particularly with a weighted mud system 6 readily controlled by the addition of a minor amount of an ethylenedicarboxylic acid. the corresponding acid anhydride or mixtures. thereof. in the range of from about 0.5 to about 6 pounds per barrel of drilling fluid. A suitable ehtylenedicarboxylic acid is maleic acid as well as the anhydride thereof. maleic anhydride. and the isomer fumaric acid.  
  The fresh water drilling fluid of the present invention contains water, a dispersed hydratable drilling clay therein. a dispersing agent for sand clayey material and the prescribed amount of the ethylenedicarboxylic acid.  
  Any suitable clay dispersing agent may be employed in the preparation of a drilling fluid or a drilling mud reagent or additive admixture in accordance with the practice of this invention, provided, of course. it is compatible with its environment in the additive admixture and/or in the drilling mud, i.e.. it is not salted out and does not undergo a chemical reaction or a physical or chemical change which would render it unsuitable or useless as a dispersing agent therein. Clay dispersing or thinning agents suitable in the practice of the invention include the lignosulfonates. such as the alkali metal lignosulfonates. the alkaline earth metal lignosulfonates and the heavy metal-containing lignosulfonates. e.g.. a lignosulfonate containing both iron and chromium. A suitable heavy metal-containgin lignosulfonate is Q- Broxin. a ferro-chrome lignosulfonate manufactured by the Puget Sound Pulp &amp; Paper Company of Bellingham. Washington. Other heavy metal-containing lignosulfonate such as iron lignosulfonate. chrome lignosulfonate. nickel lignosulfonate. lead lignosulfonate. copper lignosulfonate. manganese lignosulfonate. molybdenum lignosulfonate. ferro-chrome lignosulfonate or mixtures and complexes thereof are also suitable clay dispersing agents.  
  The drilling fluids may also include the usual water loss additives such as a prehydrolyzed starch commercially available under the tradenames lmerpmex and My-lo-gel. carboxymethycellulose (CMC) and the like.  
  The ethylenedicarboxylic acid used in the fresh water drilling fluid to restore the drilling fluid properties thereto after the drilling fluid is contaminated with a salt such as sodium or potassium chloride. is maleic acid. maleic anydride. fumaric acid and mixtures thereof in an amount of from about 0.5 to about 6 pounds per barrel. Most effective results are obtained using amounts in the range of from about 1 to about 4 pounds per barrel. especially when maleic acid or a mixture of maleic acid and maleic acid anhydride are used.  
  The drilling fluid additive for use in the practice of the present invention may comprise maleic acid. maleic acid anhydride. fumaric acid. including mixtures thereof is incorporated in the drilling fluid in an amount in the range of from about 0.5 to about 6 pounds per barrel.  
  In the accompanying table the properties of the fresh water drilling fluid were determined in accordance with 0 the established procedure set forth in the American Petroleum Institute publication, APl RP29. Fourth Edition. Yield Point (YP) is calculated by subtracting the Plastic Viscosity (PV) from the Fann Viscosity reading at 300 rpm. Plastic Viscosity (PV) is obtained by calculation. subtracting the Fann Viscosity reading at 300 rpm from the 600 rpm reading. Apparent Viscosity (AV) is equal to one-half of the Fann Viscosity (FV) reading obtained at 600 rpm. The fluidity of a drilling fluid can be back calculated from these data. the results being expressed in Fann Viscosity at 600 rpm and 300 rpm. for a direct reading viscometer.  
 many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be made as are indicated in the The table sets forth representative physical properappended claims TABLE Amount of Y? Additive PV lbs/ 1110 ApVis Cl. Example lbs/barrel cpe. ft. cpe. pH ppm.  
  Base Mud 28.5 ll 28 9.6 A. BHSL&#39; Mud 5 NaCl 311 23 41.5 9.6 13.21111 1. &#34;A 1 MlllBiC&#34;&#39; 311.5 14.5 32.11 7.11 2. &#34;A 2 Malcic 30 I) 39.5 7.5 3. &#34;A 3 Maleic&#34; 25.5 19 35 7.4 4. &#34;A +4 Malcic&#34; 19.5 21.5 311.3 7.6 B Base Mud 111 NaCl 24 53 511.5 9.6 22.350  
  5. &#34;B&#34; 1 Maleic* 33 23 44.5 7.5 6. &#34;B&#34; 2 Maleic 28 211.5 311.3 7.6 7. &#34;13 3 Maleic 221.5 l8.5 37.11 7.6 11. &#34;B&#34;+4 Maleic 21.5 21.5 32.3 7.4 L. dSfl Mud 15 NaCl 21 66 54 9.6 31.41111 9. &#34;C&#34; I Mulcic 26.5 25 39 7.6 111. C&#34; 2 Maleic 32.5 16.5 411.3 7.7 11. &#34;C 3 Maleic 311 15 37.5 7.4 12. &#34;C 4 Maleic 19.5 21 311 7.6 D. a. Mud 211 NaCl 20 67 53.5 96 49.3511  
  13. D&#34; 1 Malcic 311.5 21 41 7.5 14. &#34;D 2 Malcic 26 15 33.8 7.8 15. &#34;D 3 Maidiu 27 14 34 7.6 16. &#34;D 4 MkIILlC&#34; 24 12 7.4 E. Base Mud 211 NaCl 295 92 75.5 9.6  
 17. &#34;E&#34;+4Maleic Anhydridc 28.5 74 65.5 9.7  
  Malcic means maleic acid ties of the drilling fluid both before and after addition I claim: of the indicated materials thereto. in each example the L Method of controlling the rheology of a fresh l of mam-ml or mutenals added to the l l water drilling fluid that has been contaminated with a Show m terms of pound per barrel of dnllmg salt selected from the group consisting of sodium chlof b d H d d h h I ride, potassium chloride and mixtures thereof. by add 8 n mg m m e tiasts was top 0 6 ing to said salt contaminated drilling fluid a mud obtamed from a drilling site 1n the West Cote ethylenedlcarboxylic acld selected from the group con- Blanche Bay field. Th1s base drilling mud 1s a llghtly I 40 s1st1ng of maleic acid. fumaric acid and male1c and antreated top hole mud contammg nat1ve SOlldS. By u hydride. in an amount of from about 0.5 to about 6 lightly treated is meant that caustic has been added ounds er barrel of drmin fl id to adjust the pH [0 about 9.0 and bentonite added 16 p 2 u 3 increase the viscosity. There is incorporated in the top ethod f h m i wherem and hole mud the ferrochrome lignosulfonate dispersant ethylenedlcarboxyhc acldknown by the trade name Q-Broxin, the pH adjusted Methcd as f l Clam 1 wherein 531d m 95.11 the the mud was aged at 59 f [6 ethylenedicarboxyhc acid 1s maleic acid anhydride. hours, 4. Method as claimed in claim 1 wherein said In the above table. after the addition of the maleic hylene icarboxylic acid is fumaric acid. acid to the salt contaminated drilling fluid. each of the MeihOd as C fl med in Claim 1 wherein said Examples l-l? intelusive was aged overnight at 150F ethylenedicarboxylic ilCld lS Elddfid in an amount Of to di i h Samples from about 1 to 4 pounds per barrel.  
  The base mud and the alt ontaminated base muds 6. ln :1 method 0f drilling WCllS where in the drilling of Examples A-D inclusive were treated with sufficient fluid is pa ugh t ell In Contact with an earth a ueou ic to dj t th H di to 96 Th formation during the drilling operation in contact with pH of the muds containing maleic acid were treated 21 8111! ted &#39;O the group Consisting of sodium with a ous caustic to b i a H f 7 4 7 3 chloride. potassium chloride and mixtures thereof in The data in the table show that the drilling fluid propthe on. the improvement which comprises conerties of the alt contaminated mud a ub tantiall tacting said earth formation with a fresh water drilling improved by the addition of varying amounts of malei fluid containing clay solids dispersed therein by a clay acid thereto. The beneficial effects are also evident dispersing agent and containing from about 0,5 to over a relatively wide range of salt concentrations. about 6 pounds per barrel of drilling fluid of an With respect to the data in Example l7. it is to be noted ethylenedicarboxylic acid. said ethylenedicarboxylic that it was obtained using a different base mud system acid being effective to restore the rheology of said drilthan the one used in the other examples. The base mud ling fluid in the presence of any contaminating amounts in this example was a top hole mud treated with 6 pounds per barrel of Q-Broxin.&#34; the pH adjusted to 9.5-10. and aged for l6 hours at [50F Obviously of salt in the formation. said ethylenedicarboxylic acid being selected from the group consisting of maleic acid. fumaric acid and maleic acid anhydride.  
 erties of a fresh water drilling fluid that has been contaminated with a salt selected from the group consisting of sodium chloride. potassium chloride and mixtures thereof, which consists of a member selected from the group consisting of maleic acid. maleic anhydride. fumaric acid. and a mixture of maleic acid and maleic anhydride.  
 UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,879, 9 DATED April 22, 1975 lN\/ ENTOR(S) Thad 0. Walker It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
 In the Abstract on Page 1, beginning on line l and continuing to part of line 6 should read .6 pounds per barrel, a. drilling method. o  
 Signed and Sealed this sixth D y of January 1976 [SEAL] A ttes t:  
 RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner nj&#39;larents and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,879, 9 DATED 1 April 22, 1975 lN\/ ENTOR(S) Thad 0. Walker It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected a5 shown below:  
 In the Abstract on Page 1, beginning on line t and continuing to part; of line 6 should read .6 pounds per barrel, a drilling method.  
 Signed and Scaled this sixth D of January 19 76 [SEAL] A ttes t:  
 RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufParents and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,879,298 DATED April 22, 1975 mv emorfis) Thad 0. Walker It is certified that error appears In the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
 In the Abstract on Page 1, beginning on line and continuing to part of line 6 should read &#34;....6 pounds per barrel, a. drilling method.....&#34;  
 Signed and Scaled this AIIESI.  
 RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nj&#39;launts and Trademarks