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Method of removing inorganic scales

a technology of inorganic scales and inorganic sand, which is applied in the direction of fluid removal, borehole/well accessories, chemistry apparatus and processes, etc., can solve the problems of limiting the productive (or injective) capacity of the well, loss of formation permeability, and formation damage, so as to reduce the amount of clay in the well, inhibit or prevent swelling, and control the effect of clay migration

Inactive Publication Date: 2012-12-27
BAKER HUGHES INC
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a method for treating oil, gas, and geothermal wells using a composition containing a hydrofluoric acid source, an organosilane, a quaternary ammonium salt, and a phosphonate acid. The composition may also contain a boron-containing compound for forming a BF4 complex. The treatment prevents the formation of inorganic scales and corrosion on downhole metal tubulars, increasing the permeability of the formation and improving production. The hydrofluoric acid source is typically prepared in-situ by the reaction of hydrochloric acid and ammonium bifluoride or ammonium fluoride. The presence of the combination of the organosilane and the quaternary ammonium salt in the composition provides better control of clay migration, inhibits swelling, and prevents scale formation. The pH of the composition is typically maintained at a range of from about 0 to about 3.0.

Problems solved by technology

In the course of drilling, or during production or workover, the vast majority of oil and gas wells are exposed to conditions that ultimately lead to formation damage.
Formation damage limits the productive (or injective) capacity of the well.
The swelling and migration of formation clay reduces the permeability of the formation by obstructing the formation capillaries, resulting in a loss of formation permeability and significant reduction in the flow rate of hydrocarbons.
Upon contact of hydrofluoric acid with metallic ions present in the formation, such as sodium, potassium, calcium and magnesium, undesirable precipitation reactions occur.

Method used

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Examples

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examples 1-6

[0062]Analytical grade carbonate powder was exposed to an aqueous hydrofluoric acid solution at 70° F. The un-dissolved solid or precipitate was analyzed by X-ray diffraction technique (XRD). Table 1 presents the results of these tests wherein pH A represents the pH at the beginning of the testing and pH B represents the pH at the end of the testing.

TABLE 1Ex.CaCO3No.CompositionpH ApH BaddedCommentsComp.HF acid2.22.20.4 g / 100 ccAll carbonateEx. 1dissolved andCaF2 precipitateformed within 5minutes.Comp.HF acid1.91.90.4 g / 100 ccAll carbonateEx. 23% Dequestdissolved and2010CaF2 precipitateformed within 5minutes.Comp.HF acid2.2>4.00.4 g / 100 ccAll carbonateEx. 32.8 g / 100 ccdissolved andBoric acidCaF2 precipitateformed within 5minutes.4HF acid1.61.60.4 g / 100 ccAll carbonate3% Dequestdissolved and2010no precipitate2.8 g / 100 ccformed over 4Boric acidhours.5HF acid1.61.61.0 g / 100 ccAll carbonate3% Dequestdissolved and2060Sno precipitate4.2 g / 100 ccformed over 24Boric acidhours.6HF acid1.61.6...

example 7

[0063]The dissolution effect of the compositions of Examples 1-6 was illustrated on a formation containing calcareous minerals as follows. A composition consisting of 75 wt. % quartz, 5 wt. % kaolinite, 10 wt. % potassium-feldspar and 10 wt. % calcium carbonate (powder) was prepared. The composition was tested for its solubility in a HF acid at 150° F. over 4 and 24 hrs. After solubility testing, the un-dissolved solid or precipitate was analyzed. The experimental conditions and results are set forth in Tables 2-5. Table 2 represents the 4 hour solubility testing of the formation composition at 150° F. Tables 3-5 represent the 4 and 24 hour solubility testing of the formation composition at 150° F.

TABLE 2HF acidHF acid3% Dequest3% DequestHF acidHF acid2010HF acid2060S3% Dequest2.8 g / 100 cc2.8 g / 100 cc3% Dequest2.8 g / 100 ccAcid2010Boric acidBoric acid2060SBoric acidpH1.9 / 1.92.2 / 5.51.6 / 1.91.6 / 1.61.0 / 1.3before / afterSolubility, %14.94.414.414.79.6Quartz8779918988Plagioclasend11nd1K-feld...

example 8

[0065]A coreflood study was conducted using a Bandera Sandstone core at 180° F. The composition of Bandera Sandstone is set forth in Table 6:

TABLE 6Mineral CompositionWt %Quartz61Feldspar15Dolomite5Illite12Kaolinite4Chlorite2

Table 7 shows the composition of acids systems used in the coreflood experiment wherein HV represents an organophosphonate.

TABLE 7Pre-Flush acidMain acidPost-Flush acidSystemsystemsystemHF, wt %—3—HCl, wt %10210HV, gpt—60—Iron control agent, gpt—10—Corrosion inhibitor, gpt 22 2Acetic acid, wt %—3—Boric Acid, ppt—60—

Five fluid stages were injected in the following sequence:[0066]1. 5 wt % NH4Cl solution to measure initial core permeability.[0067]2. 4 pore volumes (PV) of Pre-Flush acid system.[0068]3. 4 PV of Main acid system.[0069]4. 4 PV of Post-Flush acid system.[0070]5. 5 wt % NH4Cl solution to measure initial core permeability.

The results of two coreflood experiments are shown in Table 8. All acid solutions injected in the second experiment contained the com...

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Abstract

The productivity of hydrocarbons from hydrocarbon-bearing calcareous or siliceous formations is enhanced by contacting the formation with a well treatment composition which contains a hydrofluoric acid source, a phosphonate acid, ester or salt thereof, a quaternary ammonium salt and an organosilane and, optionally, a boron-containing compound.

Description

[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 12 / 861,390 which is a continuation of U.S. patent application Ser. No. 11 / 901,578, filed on Sep. 18, 2007, now U.S. Pat. No. 7,781,381.FIELD OF THE INVENTION[0002]The invention relates to a method of enhancing the productivity of a hydrocarbon bearing siliceous or calcareous formation by use of a well treatment composition which contains a phosphonate acid, ester or salt, a hydrofluoric acid source, a quaternary ammonium salt and an organosilane.BACKGROUND OF THE INVENTION[0003]In the course of drilling, or during production or workover, the vast majority of oil and gas wells are exposed to conditions that ultimately lead to formation damage. Formation damage limits the productive (or injective) capacity of the well. The reduction in well performance is generally due to changes in near-wellbore permeability which may be caused by a number of factors, such as rock crushing, invasion of drill solids, ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): E21B37/06
CPCC09K8/78C09K8/528
Inventor QU, QIGOMAA, AHMED MOHAMED MOHAMED
Owner BAKER HUGHES INC
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