FR2518109A1 - ACTIVATION OF HYDROXYETHYLCELLULOSE FOR USE IN BRINE - Google Patents

Abstract

MODIFYING VISCOSITY COMPOSITION CONTAINING HYDROXYETHYLCELLULOSE SUSPENDED IN CERTAIN POLAR ORGANIC LIQUIDS, THE COMPOSITION HAVING AGED FOR A PERIOD OF TIME SUFFICIENT TO ACTIVATING HYDROXYETHYLCELLULOSE IN SUSPENSION OF MANHIERE HYDROXYETHYLCELLULOSE IN MANY POSHIERE DOSE OF MANHIERE HYDROXYETHYLCELLULOSE. AT APPROXIMATELY 1.6GCM AT ROOM TEMPERATURE. APPLICATION TO THICK AQUEOUS FLUIDS USED IN THE OIL AND GAS INDUSTRY.

Description

25181 O 9

  The present invention relates to dense brine solutions, more particularly to dense brines so-called having a density greater than about 1.6 g / cm 3 and processes for activating hydroxyethylcellulose

  for use as a viscosity modifier in such brines.

  Thickened aqueous media, especially those containing oilfield brines, are commonly used as night-time maintenance and repair fluids such as drilling fluids, reconditioning fluids, completion fluids, sealants, fluids for the treatment wells, fluids for the treatment of subterranean formations, spraying fluids, well-abandoning fluids and other aqueous fluids for which an increase in viscosity is desired. It is known to use

  hydrophilic polymers such as hydroxyethyl cellulose (HEC) as thickeners

  However, HEC does not hydrate, dissolve or disperse readily in aqueous systems having a density greater than about 1.6 g. Without high temperature and / or high shear mixing for prolonged periods of time For example, hydroxyethyl cellulose polymers are weakly hydrated, solvated or dispersed in aqueous solutions containing

  one or more salts of multivalent water-soluble cations, such as

  densities commonly used in well maintenance and repair fluids In many cases, such as during

  reconditioning, the equipment available for the preparation of

  maintenance and repair work does not lend itself easily to

  high erosion and high shear mixing, which is why it is

  necessary, if you wish to use these thickened brines,

prepare far from the drilling site.

  The prior art indicates that it is conventional to disperse the HEC in an organic medium such as ethylene glycol or alcohols before introducing it.

  in an aqueous liquid to obtain a good dispersion of HEC The prior art

  Furthermore, the HEC is swollen in certain organic media, especially in the case of ethylene glycol. When the HEC is suspended in ethylene glycol or in an organic medium which swells the HEC, the prior art indicates that the The suspension should be added immediately to the aqueous liquid, otherwise the HEC will swell, resulting in poor dispersion in the aqueous liquid. Thus, the use of ethylene glycol and other organic liquids that swell HEC are not recommended for suspending

from the HEC.

  It is disclosed in U.S. Patent Application Ser. No. 119,805, filed Feb. 8, 1980, entitled "Dispersible Hydrophilic Polymer Compositions" that HEC can be suspended with a polar organic liquid which swells in the water. HEC and in an organic liquid that does not swell the HEC and then let the mixture age for a period of time such that the HEC is

  disperses and hydrates well in dense brines.

  The Applicant has now found that the HEC can be activated so that it readily hydrates in dense brines at room temperature by suspending the HEC in an organic liquid which swells the HEC and

  allowing the slurry to age for a time sufficient to activate the HEC.

  It is therefore an object of the present invention to provide

  new compositions containing hydroxyethylcellulose for the purpose of

  viscosity determination of dense brines having a density greater than about 1.6 g / cm 3 which comprises about 10% to about 25% by weight of HEC pasted in an organic liquid which swells HEC, the composition having undergone

  aging for at least two hours at room temperature.

  Another object of the present invention is to provide a method for activating

  of HEC so that HEC is hydrated at room temperature in

  dense brines, said process consisting in impregnating the HEC with an organic liquid

  that inflates the HEC and allow the suspension to age for at least two

hours at room temperature.

  Yet another object of the invention is to provide a method for increasing the

  the viscosity of an aqueous solution with a viscosity greater than

  approximately 1.6 g / cm 3, which consists in adding to the solution a modifying composition

  viscosity composition comprising about 10% to about 20% by weight of pasted HEC

  in an organic liquid which swells the HEC, the composition having undergone an

  for at least two hours at room temperature.

  These and other objects of the invention will emerge more clearly from

  the description provided and the appended claims.

  Activation of HEC so that it hydrates in dense brines at room temperature is accomplished as follows according to the present invention. The particulate HEC is first mixed with a polar organic liquid ( POL) which swells the HEC and the mixture is then aged for

  hands two hours at room temperature.

  Many compounds can be used as POL, depending on the end use of the thickening agent. To determine whether a particular compound or substance acts as a POL according to the present invention, a simple test such as follows: one (1) by weight of the HEC polymer is uniformly mixed using a spatula with two (2) parts by weight

  of the POL concerned. The mixture is then allowed to stand idle

  The liquids which are useful as POL produce, when subjected to the test protocol, solid, semisolide or viscous mixtures which are substantially free from liquid in the mixture in Drès. In general, it has been found that virtually any organic compound that satisfies the solvation test described above acts, a usable degree, as the preferred non-limiting POLs.

  aliphatic glycols containing 2 to 5 carbon atoms such as ethylene.

  glycol, 1,2-propanediol, 1,4-butanediol, 1,3-pentanediol and the like

  alkaryl triols containing 2 to 6 carbon atoms such as olycoleol, 1,2,3-butanetriol, 1,2,3-pentanetriol and the like; amides having 1 to 4 carbon atoms such as formamide, acetamide, dimé

  thylformamide and the like and mixtures of the various compounds above.

  In the formulation of the viscosity modifying agents of the present invention,

  In the present invention, it is preferable for ease of handling that the POL is present in an amount such that the viscosity modifier,

  the composition of activated HEC remains a pourable liquid after aging.

  For a period of time sufficient to activate HEC, it is thus that ethylene glycol and glycerol, which are the polar organic liquids preferred for use in this invention, produce dimer modifiers. liquid and flowable viscosities at concentrations greater than about 80% by weight Other less effective POLs may produce

  liquid viscosity castable at concentrations greater than about 75%.

  A concentration of POL greater than about 90% would be excessive and unnecessary. Thus, the concentration of HEC in the viscosity modifying composition should be between about 10% and about 25% by weight, preferably 1% to about 25% by weight.

  about 10% and about 20% by weight.

  The mixture of HEC and POL for increasing the viscosity of dense brines is activated by allowing the mixture to age for at least three hours. The activation can be carried out in a shorter time at high temperatures. It has been found that if the concentration of HEC in the POL / is such that a celified composition is obtained after activation, the gel efficiency of the viscosity modifier composition decreases and may be totally ineffective after further aging. of the composition This is how the activated HEC compositions will have to be

  used prior to gelation of the composition.

  The activated HEC composition may be used wherever HEC is required However, activation of HEC is only necessary when used in dense brines having a density greater than about 1.6 g / cm In recent years, the practical operating range of clear brines for the oil and gas industry has expanded significantly through the use of soluble zinc salts, particularly bromide bromide. zinc, so that the benefits of clear brines can now be achieved with fluids with similar densities

  higher than 2.3 q / cm 3 at normal temperatures and pressures.

  Clear, high density brines are widely used as completion fluids to minimize filling of perforation tunnels, to protect the permeability of formation and to minimize mechanical problems; as reconditioning fluids for the same reasons; as sealing fluids to allow easy movement and

  packer recovery; for enlargement and consolidation applications

  gravel and sand; as an injection fluid or as a balancing fluid

  last; for working on the cable and as drilling fluids.

  Clear brines having a density of 1.7 a / cm 3 or less are generally formulated to contain sodium chloride, sodium bromide, potassium chloride, calcium chloride, calcium bromide or mixtures thereof. of these salts Brines having a density up to about 1.8 g / cm 3 can be formulated with calcium chloride and

  calcium bromide; however, if the brine must have a low temperature,

  crystallization, brines clear in this density limit are then generally formulated to contain a soluble zinc salt

  prefers zinc bromide because the brines containing it are less corro-

  than those containing zinc chloride Brines with a density greater than about 1.8 g / cm 3 are formulated to contain

zinc bromide.

  HEC is usually present in dense brine at a concentration

  from about 2.85 g / liter to about 14.3 g / liter.

/ 251e 109

  For a more complete illustration of the invention,

  the following non-limiting example.

Example

  Three samples containing 10%, 15% and 20% MATROSOL 250 HHR in ethylene glycol V were prepared by mixing the HEC

  and ethylene glycol for 30 seconds Each sample was immediately

  2.degree. per liter in a Ca Br 2 / Zn Br 2 solution at 0.19 g / cm 2 by hand shaking the sample and the solution for 30 seconds and stirring the mixture in a viscometer. Fann VG at 300 rpm The dial reading at 300 rpm was done after and 60 minutes as shown in Table 1 and after rotating the brines overnight at 65.50 C. Each sample was then evaluated after some aging time as indicated in the

table 1.

  The numbers show that the samples must undergo

  aging for the HEC to hydrate in this solution.

  10% HEC remained flowable for 48 hours.

  20% HEC excessively gelled after aging.

  during a period sufficient for the activation of the HEC, so that the gelled particles formed lumps and could not

  be dispersed even after a hot rotation.

  It is indicated a minimum aging time of about

  2 hours, preferably at least 3 hours.

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TABLE 1 (S Ilite)

  N. (2) Old Brookfield Viscosity (3) HEC qualitative viscosity at 2.85 g / l in

  #cp * 6 rpm of the sample at 1.9 cd / c; lli 3, reading

hours at V-G Fann at 300 t / inin.

Length of time

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53 25 81 Q 9

Claims (12)

  A viscosity modifying composition comprising about 10% to about 25% by weight of hydroxyethylcellulose in a polar organic liquid, said polar organic liquid, when uniformly mixed with said hydroxyethylcellulose in a weight ratio of hydroxyethyl cellulose to liquid 1: 2 polar organic product, produced a mixture with almost total absence of free liquid after a repo period of one week at room temperature in a sealed container, said composition having undergone a   aging for a period of time sufficient to   hydroxyethylcellulose so that the hydroxyethylcellulose   cellulose is hydrated in dense brines with a   density greater than about 1.6 g / cm 3 at room temperature.   you. 2 Composition according to claim 1, characterized 6 risée   in that the concentration of hydroxyethylcellulose is   between about 10% and about 20% by weight.   3.Composition according to one of claims 1 or 2,   characterized in that said polar organic liquid is selected from the following: ethyllneglycol, glycerol, and mixtures thereof.   4.Composition according to one of claims 1 or 2,   characterized in that said polar organic liquid is selected from aliphatic glycols containing 2 to 5 carbon atoms, alkylene triols containing 3 to 5 carbon atoms, amides containing 1 to 4 carbon atoms and mixtures thereof.   Composition according to any one of the claims   1 to 4, characterized in that it has undergone aging   for at least two hours at room temperature.   6.Composition according to any one of the claims   1 to 4, characterized in that it knew Di aging   for at least three hours at room temperature.   7.Composition according to any one of the claims   1 to 4, having aged for at least two   hours at room temperature, the concentration of hydro-   2518 Io 09 xyethylcellulose being such that said composition is a pourable liquid after activation.   9.A method of activating hydroxyethylcellulose such as hydroxyethylcellulose hydrates in dense brines having a density of greater than about 1.6 g / cm 3 at room temperature, said method comprising impregnating said hydroxyethylcellulose at a concentration of from about 1 to about 25% by weight of a polar organic liquid and subjecting said suspension to aging for a period of time.   a period of time sufficient to activate said hydroxy-   ethylcellulose, said polar organic liquid, when uniformly mixed with said hydroxyethylcellulose in a weight ratio of hydrocyethylcellulose to polar organic liquid of 1: 2, producing a mixture with almost no   free liquid after a rest period of one week.   do not at room temperature in a sealed container.   9.Procédé according to claim 8, characterized in that said concentration of hydroxyethylcellulose is   from about 10% to about 20% by weight.   Process according to one of claims 8 or 9,   characterized in that said polar organic liquid is selected from the following: ethylene glycol, glycerol and mixtures thereof.   11.Procédé according to one of claims 8 or 9, charac-   characterized in that said polar organic liquid is selected from aliphatic glycols containing 2 to 5 carbon atoms.   carbon, alkylene triols containing 3 to 5 carbon atoms   bone, amides containing 1 to 4 carbon atoms and mixtures thereof.   Process according to any one of the claims   8 to 11, characterized in that said period of time is   at least two hours at room temperature.   13.Procedure according to any one of the claims   8 to 12, characterized in that said period of time is at least two hours at room temperature and that the concentration of hydroxyethylcellulose is such that said   composition is a flowable liquid after activation.   14.Procédé according to any one of the claims   8 to 12, characterized in that said period of time is at least three hours at room temperature and that the concentration of hydroxyethylcellulose is such that said composition is a flowable liquid after activation. 15.A process for increasing the viscosity of an aqueous solution having a density greater than about   1.6 g / cm 3 of mixing with said solution the   viscosity modifying position according to any one of   claims 1 to 4 in an amount sufficient to   to increase the viscosity of said solution.   16.A method of increasing the viscosity of an aqueous solution having a density greater than about 1.6 g / cm 3 by mixing with said solution the viscosity modifying composition according to which   conque of claims 1 to 4 having undergone aging   at least two hours at room temperature in an amount sufficient to increase the viscosity of said solution. A process for increasing the viscosity of an aqueous solution having a density greater than about 1.6 g / cm 3 by mixing with said solution the viscosity modifying composition according to one of   any of claims 1 to 4 having undergone an aging   at least three hours at room temperature, in an amount sufficient to increase the viscosity of said solution.   18. A process for increasing the viscosity of an aqueous solution having a density greater than about 1.6 g / cm 3 comprising mixing with said solution.   viscosity modifying composition according to any one of   that claims 1 to 4 having undergone aging   at least two hours at room temperature, the concentration of   The use of hydroxyethylcellulose is such that said composition is a flowable liquid after activation in an amount sufficient to increase the viscosity of said solution.