Treating shale and clay in hydrocarbon producing formations

Information

  • Patent Grant
  • 6502637
  • Patent Number
    6,502,637
  • Date Filed
    Tuesday, March 20, 2001
    23 years ago
  • Date Issued
    Tuesday, January 7, 2003
    21 years ago
Abstract
Clay is stabilized in the drilling of wells and other formation treatment for hydrocarbon production by the addition to the drilling or other fluid fluid of potassium formate together with a cationic formation control additive.
Description




TECHNICAL FIELD




This application relates to the drilling of wells in the production of oil, gas and other fluids from underground formations, and particularly to the stabilization of boreholes drilled for the production of hydrocarbons. It includes the treatment of shale and clay in situ to prevent swelling caused by the absorption of water from drilling fluids.




BACKGROUND OF THE INVENTION




A good description of the problem which this invention addresses in the context of formation drilling may be found in an article by Thomas W. Beihoffer et al in the May 16, 1992 Oil & Gas Journal, page 47 et seq., entitled “Cationic Polymer Drilling Fluid Can Sometimes Replace Oil-based Mud.” As stated therein, “(S)hales can become unstable when they react with water in the drilling fluid. These reactive shales contain clays that have been dehydrated over geologic time by overburden pressure. When the formation is exposed, the clays osmotically imbibe water from the drilling fluid. This leads to swelling of the shale, induced stresses, loss of mechanical strength, and shale failure.” Shale crumbling into the borehole (“sloughing”) can ultimately place a burden on the drill bit which makes it impossible to retrieve.




Salts such as potassium chloride have been widely used in drilling treatments to convert the formation material from the sodium form by ion exchange to, for example, the potassium form which is less vulnerable to swelling; also the use of high concentrations of potassium salts affects the osmotic balance and tends to inhibit the flow of water away from the high potassium salt concentrations into the shale. However, it is difficult to maintain the required high concentrations of potassium salts in the drilling fluids. In addition, the physical introduction of such salts causes difficulties with the preparation of the viscosifying materials typically used for drilling. Inorganic salts can also have a harmful effect on the environment if released.




As background for the present disclosure, I have assembled prior art references representative of three general types of amine and quaternary ammonium cation sources which have been suggested for clay treatment in hydrocarbon recovery. These are (a) single-site quaternaries and amines, (b) compounds having a few (two to about six) amine or quaternary ammonium cation sites, which I have called “oligocationic”, and (c) quaternary ammonium or amine polymers, which may have from about six to thousands of cationic sites. The entire specifications of all of the patents set forth below are incorporated by reference, as the cationic materials described therein are useful in my invention.




A. Single-Site Quaternaries and Amines: Brown U.S. Pat. No. 2,761,835, Brown U.S. Pat. No. 2,761,840, Brown U.S. Pat. No. 2,761,836, Himes et al U.S. Pat. No. 4,842,073, Thomas and Smith U.S. Pat. No. 5,211,239.




B. Oligocationics: Brown U.S. Pat. No. 2,761,843; Krieg U.S. Pat. No. 3,349,032.




C. Polycationics: Borchardt et al U.S. Pat. No. 4,447,342, McLaughlin et al U.S. Pat. No. 4,374,739 McLaughlin et al U.S. Pat. No. 4,366,071.




SUMMARY OF THE INVENTION




My invention includes the use of combinations of potassium formate with various cationic materials, for the treatment of clay and shale in subterranean formations during drilling and otherwise for the stabilization of clay and clay-containing shale. For purposes of this patent application, it should be noted that all of the above identified patents incorporated by reference address problems similar to the problem I address. Each of the patents employs cationic formation control additives for drilling fluids to help control the swelling and sloughing of shale and clay contacted by aqueous drilling and other formation treating fluids. The contexts of use of such additives and the techniques for employing them as described in those patents are entirely consistent with and compatible with my invention. That is, I employ my own combination of additives in drilling fluids and otherwise to treat shale and clay to control swelling and sloughing.




Although the entire specifications of the above listed patents are incorporated by reference, to help in defining the materials useful in the present invention, I refer specifically to parts of the above identified patents, namely:




Brown U.S. Pat. No. 2,761,835 columns 3-10, Brown U.S. Pat. No. 2,761,840 columns 5-6, Brown U.S. Pat. No. 2,761,836 columns 5-6, Himes and Vinson U.S. Pat. No. 4,842,073 columns 1-10, Thomas and Smith U.S. Pat. No. 5,211,239 columns 1-2, Brown U.S. Pat. No. 2,761,843 columns 3-6, Krieg U.S. Pat. No. 3,349,032 columns 3-12, McLaughlin et al U.S. Pat. No. 4,366,071 columns 7-14, and Borchardt et al U.S. Pat. No. 4,447,342 columns 17-20.











It will be seen from these passages and excerpts (the full disclosures of the patents, as indicated above, are incorporated in their entireties) that the three general types of cationic materials I may use in my invention for the stabilization of clay in subterranean formations are single-site cationics, oligocationics, and polycationics. Together they may be referred to herein as “cationic formation control additives.” Although cationics derived from sulfur, phosphorous and other elements capable of forming water-soluble cationic sites are effective and included in my invention, I prefer to use amine or ammonium-based cations. Thus the cationic portion of my clay treatment composition is preferably an amine or ammonium based (succinctly, “nitrogen-based”) cationic material. I may use any of the cationic materials described in the above identified patents.




The single site amine and quaternaries useful as cationic formation control additives in my invention include di-, tri, and tetra- alkyl substituted amine and ammonium compounds wherein the alkyl groups include from 3 to 8 carbon atoms (Brown U.S. Pat. No. 2,761,835); substituted pyridine, pyridinium, morpholine and morphilinium compounds having from 1 to 6 carbon atoms in one or more substituent groups (Brown U.S. Pat. No. 2,761,840), additional heterocyclic nitrogen compounds such as histamine, imidazoles and substututed imidazoles, piperazines, piperidines, vinyl pyridines,and the like as described in Brown U.S. Pat. No. 2,761,836, the trialkylphenylammonium halides, dialkylmorpholinium halides and epihalohydrin derivatives described by Himes et al in the U.S. Pat. No. 4,842,073 patent, and the allyl ammonium compounds of the formula (CH


2


═CHCH


2


)


n


N


+


(CH


3


)


4-n


X





where X





is any anion which does not adversely react with the formation or the treatment fluid, described by Thomas and Smith in U.S. Pat. No. 5,211,239. Preferred single site quaternaries are diallyl dimethyl ammonium chloride (that is, the above formula where n═2 and X





is Cl





), and tetramethyl ammonium chloride, sometimes referred to as TMAC.




Oligocationics useful as cationic formation control additives in my invention include di- and polyamines (up to 100 nitrogens) substituted with alkyl groups having up to 12 carbon atoms (one or more of the nitrogens may be quaternized) as described by Brown in U.S. Pat. No. 2,761,843, and polyquaternaries described by Krieg in U.S. Pat. No. 3,349,032, namely alkyl aryl, and alkaryl bis- and polyquaternaries wherein two quaternary ammonium nitrogens are connected by various connecting groups having from 2-10 carbon atoms.




Polyquaternary (cationic) formation control additives useful in my invention include those described by McLaughlin in the U.S. Pat. No. 4,366,071 and U.S. Pat. No. 4,374,739 patents, namely polymers containing repeating groups having pendant quaternary nitrogen atoms wherein the quaternizing moieties are usually alkyl groups but which can include other groups capable of combining with the nitrogen and resulting in the quaternized state. I may also use any of the numerous polymers including quaternized nitrogen atoms which are integral to the polymer backbone, and other polymers having repeating quaternized units, as described by Borchardt in the '342 patent. Nitrogen-based cationic moieties may be interspersed with and/or copolymerized with up to 65% by weight (preferably 1% to 65% by weight) nonionics such as acrylamide and even some anionics such as acrylic acid or hydrolyzed acrylamide. Molecular weights of the polymers may be quite high —up to a million or more. Such copolymers are included in my definition: of polycationic formation control additives useful in my invention.




Preferred anions for association with the quaternized nitrogen atoms are halide anions, particularly chloride ions, which readily dissociate in the aqueous drilling or other formation treatment fluid, but any anions, including formate anions, may be used which will not interfere with the purposes of the formation treatment. Persons skilled in the art may wish to review the various anions mentioned in the above incorporated patents.




Thus it is seen that a cationic formation control additive useful in my invention is a material having from one to hundreds or thousands of cationic sites, generally either amines or quaternized amines, but may include other cationic or quaternized sites such as phosphonium or sulfonium groups.




I employ potassium formate together with a cationic formation control additive. The potassium formate may be added to the formation treating or drilling fluid before or after the cationic formation control additive, or may be made in situ by the reaction of potassium hydroxide and formic acid. The potassium hydroxide and formic acid may be added in any order, separately or together, before or after the addition of the cationic formation control additive, and need not be added in exact molar proportions. Any effective amount of the combination of potassium formate and formation control additive may be used, but I prefer to use ratios of potassium formate to formation control additive of 25:75 to 75:25 by weight in the solution, in combined concentrations of at least 0.001% by weight in the drilling or other formation treatment fluid. Following are results from a clay pack flow test and a capillary suction test.















Clay Pack Flow Test






Volume (higher the better)













Elapsed time →



















1 min-




3 min-




5




10




CST






Test products




start




ute




utes




min




min




time




















Fresh water




5




15




17




23




25




225.2






2% KCl




15




87




175






102






1% KCl and




19




80




132




172





36.1






12 GPT KCOOH






poly(DADMAC) 2 GPT




26




90




140




185





38.3






poly(DADMAC) +




21




83




132




170




212




45.6






KCOOH 2 GPT






poly(DADMAC) 1 GPT




22




52




72




86




112




63.8






poly(DADMAC) +




21




74




112




140




179




40.9






KCOOH 1 GPT






poly(DADMAC) +




5




21




28




34




47




224.6






0.5 GPT






poly(DADMAC) +




18




55




80




107




146




58.6






KCOOH 0.5 GPT






LMWP (DADMAC)




14




42




64




82




107




68.4






2 GPT






LMWP (DADMAC)




19




64




83




118




156




57






2 GPT + KCOOH






HMWP (DADMAC/AA)




8




26




38




48




60




165.8






2 GPT






HMWP (DADMAC/




17




48




71




88




114




60.6






AA) + KCOOH 2 GPT






Monomer (DADMAC)




2




17




22




30




42




239.6






2 GPT






KCOOH (37%)




7




25




31




41




51




168.7






2 GPT






Champion TMAC




1




36




63




75




109




146.4






2 GPT






Champion TMAC




3




23




33




39




47




263.9






1 GPT






TMAC 1 GPT +




15




59




95




124




172




68.9






12 GPT KCOOH











Poly(DADMAC) = 25% poly(diallyldimethyl ammonium chloride)










TMAC = 25% by weight tetramethyl ammonium chloride










GPT = gallons of the test additive(s) solution per thousand gallons of formation treatment (drilling) fluid










HMWP = 15.5% by weight of the indicated high molecular weight polymer










LMWP = 14.5% by weight of the indicated low molecular weight polymer










KCOOH = 18% by weight aqueous solution













From the above table, it can be seen that the addition of potassium formate to the formation control additives improved the results considerably. In the clay pack flow test, where the higher volumes at a given time indicate better clay stability, the addition of a small amount of potassium formate increased the volume throughput for a given polymer concentration. In fact, adding the potassium formate improved the performance of a polymer more than using twice the concentration of the polymer alone. For example, the poly(DADMAC) at 1 GPT treatment had a volume at 10 minutes of 112 ml. The same polymer, when combined with potassium formate and treated at 0.5 GPT (half the original polymer concentration), had a volume of 146 ml, indicating better clay stability and a possible synergistic effect from the addition of the potassium formate.




Similar results are obtained from the CST data. In this test, a constant volume of treated fluid is flowed across a clay and filter medium. The lower the time for the volume to pass through, the better the clay stabilization. The addition of potassium formate lowers the CST time in nearly all cases, indicating a benefit in performance from the formate. The presence of potassium formate, as in the clay pack flow test, also indicates synergy with the polymer. The CST time for the poly(DADMAC) +potassium formate at 0.5 GPT is lower than the time for the higher concentration (1 GPT) of polymer alone. Thus, the addition of potassium formate is sufficiently beneficial to allow reducing the polymer by half, and still increase the performance.




In both the clay pack flow test and the CST, the polymer combinations with the potassium formate were also better than the effect of formate alone. The CST result and the clay pack flow test volume for the 2 GPT of 37% potassium formate (by itself) were both worse than even the low treatment levels of the polymer/formate combinations, but better than some of the polymer treatments alone. This indicates that, while the potassium formate is effective alone and better than some polymer-only treatments, its performance is enhanced when combined with the formation control additives.



Claims
  • 1. Method of reducing permeability damage in a subterranean formation from contact of a treatment fluid with said subterranean formation comprising contacting the subterranean formation with an aqueous solution of said treatment fluid containing a nitrogen-based cationic formation control additive and potassium formate.
  • 2. Method of claim 1 wherein said potassium formate is present in said aqueous solution in a ratio of 25:75 to 75:25 by weight to said cationic formation control additive in a total concentration in said treatment fluid of at least 0.001% by weight.
  • 3. Method of claim 1 wherein said cationic formation control additive is a polymer of dimethyl diallyl ammonium chloride.
  • 4. Method of claim 1 wherein said cationic formation control additive is a homopolymer of dimethyl diallyl ammonium chloride having a molecular weight from about 1000 to about 500,000.
  • 5. Method of claim 1 wherein said potassium formate is generated in situ by the reaction of formic acid and potassium hydroxide or carbonate.
  • 6. Method of claim 1 wherein said formation control additive is a single site amine or quaternary ammonium compound.
  • 7. Method of claim 1 wherein said formation control additive is an oligocationic compound.
  • 8. Method of claim 1 wherein said formation control additive is a cationic polymer.
  • 9. Method of claim 2 wherein said cationic formation control additive is tetramethyl ammonium chloride.
RELATED APPLICATION

This application is based upon Provisional Application Ser. No. 60/192,304 filed Mar. 27, 2000, and claims the full benefit of its disclosure, claims and filing date.

US Referenced Citations (23)
Number Name Date Kind
2761835 Brown Sep 1956 A
2761836 Brown Sep 1956 A
2761840 Brown et al. Sep 1956 A
2761843 Brown Sep 1956 A
3349032 Krieg Oct 1967 A
4164979 Nooner Aug 1979 A
4366072 McLaughlin et al. Dec 1982 A
4374739 McLaughlin Feb 1983 A
4447342 Borchardt et al. May 1984 A
4536297 Loftin et al. Aug 1985 A
4647859 Son et al. Mar 1987 A
4693639 Hollenbeak et al. Sep 1987 A
4842073 Himes et al. Jun 1989 A
4974678 Himes et al. Dec 1990 A
4977962 Himes et al. Dec 1990 A
5211239 Thomas et al. May 1993 A
5363918 Cowan et al. Nov 1994 A
5607902 Smith Mar 1997 A
5620947 Elward-Berry Apr 1997 A
5635458 Lee et al. Jun 1997 A
6006831 Schlemmer et al. Dec 1999 A
6124244 Murphey Sep 2000 A
6156708 Brookey et al. Dec 2000 A
Foreign Referenced Citations (1)
Number Date Country
WO9514066 May 1995 WO
Non-Patent Literature Citations (3)
Entry
Beihoffer Et Al “Cationic Polymer Drilling Fluid Can Sometimes Reylace Oil-Based Mud” Mar. 16, 1992 Oil & Gas Journal pp. 47-52.
R.E. Himes, E.F. Vinson & D.E. Simon “Clay Stabilization in Low Permeability Formations” Mar. 13, 1989 Society of Petroleum Engineers SPE 18881 pp. 507-516.
Ronald P. Steiger “Fundamentals and use of Potassium/Polymer Drilling Fluids to Minimize Drilling and Completion Problems Associated With Hydratable Clays” Aug. 1982 SPE 10100 Pp.
Provisional Applications (1)
Number Date Country
60/192304 Mar 2000 US