CA2045260A1 - Method for prolonging the useful life of scale inhibitors injected within a formation - Google Patents
Method for prolonging the useful life of scale inhibitors injected within a formationInfo
- Publication number
- CA2045260A1 CA2045260A1 CA 2045260 CA2045260A CA2045260A1 CA 2045260 A1 CA2045260 A1 CA 2045260A1 CA 2045260 CA2045260 CA 2045260 CA 2045260 A CA2045260 A CA 2045260A CA 2045260 A1 CA2045260 A1 CA 2045260A1
- Authority
- CA
- Canada
- Prior art keywords
- scale inhibitors
- polyquaternary
- amine
- formation
- scale
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
METHOD FOR PROLONGING THE USEFUL LIFE
OF SCALE INHIBITORS INJECTED WITHIN A FORMATION
A method is disclosed for prolonging the useful life of scale inhibitors injected within a formation. This method involves injecting an aqueous solution of polyquaternary amines into the formation. This solution of polyquaternary amines can be injected either prior to or simultaneously with the injection of the scale inhibitors. The scale inhibitors are preferably non-polymeric scale inhibitors. Preferably, the polyquaternary amine is a poly(dimethylamine-co-epichlorohydrin) or a poly(diallyldimethylammonium chloride).
METHOD FOR PROLONGING THE USEFUL LIFE
OF SCALE INHIBITORS INJECTED WITHIN A FORMATION
A method is disclosed for prolonging the useful life of scale inhibitors injected within a formation. This method involves injecting an aqueous solution of polyquaternary amines into the formation. This solution of polyquaternary amines can be injected either prior to or simultaneously with the injection of the scale inhibitors. The scale inhibitors are preferably non-polymeric scale inhibitors. Preferably, the polyquaternary amine is a poly(dimethylamine-co-epichlorohydrin) or a poly(diallyldimethylammonium chloride).
Description
2 ¦METHOD FOR PROLONGING THE USEFUL LIFE
3 ¦OF SCALE INHIBITORS INJECTED WITHIN A FORMATION
, 4 I
¦The present invention relates to the scale inhibitor squeeze process applied in6 production wells.
8 ¦BAt~KGRouND OF THE INVENTION
10 ¦Scale inhibitors are applied in production wells to prevent precipitation of11 ¦ water-borne deposits, such as barium sulfate, calcium carbonate, and calcium sulfate.
12 ¦ Such precipitates can hinder fluid production by blocking the flow paths either inside 13 ¦ the formation or at the perforations. Scale deposition also can appear in the tubing, 14 ¦ slowing fluid production and damaging downhole equipment.
16 ¦ Qne common method of applying a scale inhibitor is the "squeeze process."
17 ¦ The steps involved in the squeeze process include:
19 ¦1. injecting the aqueous scale inhibitor solution (often a low percent inhibitor 20concentration), 22 ¦2. injecting an overflush brine solution to push the scale inhibitor several feet 23 ¦away from the wellbore, 25 ¦3. shutting-in the well for about a day to allow maximum retention of the 276inhibitor on the rock surfaces, and I I ;~0~ 26~) 2 ¦ 4. putlhlg the well b~ck on normal production.
3 l ¦ The produced water then slowly leaches the retained scale inhibitor from the 5 ¦ formation. Ideally this places a low, but still effective, concentration ~typically a low 6 I mg/l) of the scale inhibitor into the produced water to prevent scale deposition for many weeks or even months.
9 ¦ Figure 1 illustrates the usual return scale inhibitor concentrations from a lo ¦ squeeze treatment. The response from such a treatment often shows:
12 ¦ 1. a short period of no inhibitor while the overflush is produced back;
14 ¦ 2. a rapid increase of inhibitor concentration for a short time, representing 15 ¦ material not retained well in the formation; and 17 ¦ 3. a gradual decline of inhibitor cor.centration.
19 ¦ This continues until the inhibitor concentration finally falls to the rninimum ~0 ¦ effective concentration. The "squeeze lifetime" is the length of time to this point.
21 ¦ Then the squeeze must be repeated.
22 ¦
23 ¦ The squeeze process is chemically inefficient. The inhibitor concentration is 24 ¦ higher than necessary, particularly in the early s~ages, and a significant amount of the 25 ¦ inhibitor often remains adsorbed inside the formation after the squeeze. Usually two-26 ¦ thirds of the injected scale inhibitor is wasted.
~ 5~6 l l 2 I Figure 1 also shows an ideal scale inhibitor return curve. Once the overflush is 3 ¦ brought back, the inhibitor desorbs into the produced water such that the chemical ¦ concentration is just above the minimum effective level. This continues until all 5 ¦ squeezed inhibitor is released from the formation. Such an ideal process would have a 6 ¦ chemical efficiency of almost 100%, or equivalently, a longer squeeze life with the 7 ¦ same amount of scale inhibitor.
8 l 9 ¦ SUMMARY OF TH~ yENTloN
11 ¦ The present invention is a method for prolonging useful life of scale inhibitors 12 ¦ injected within a formation. This method involves injecting an aqueous solution of 13 ¦ polyquaternary amines into the formation. That solution of polyquaternary amines can 14 ¦ be injected either before or with the injection of the scale inhibitors.
16 ¦ Preferably, the scale inhibitors are non-polyrneric scale inhibitors, such as 17 ¦ amine phosphonates. Useful amine phosphonates include aminotri (methylene 18 ¦ phosphonic acid~ and diethyltriatninepenta (methylene phosphonic acid).
20 ¦ Preferably, the polyquaternary amine is either a poly(dimethylamine-co-21 ¦ epichlorohydrin) or a poly(diallyldimethylammonium chloride).
23 ¦ The present invention also involves a method for inhibiting scale buildup within 24 ¦ a formation surrounding a production well. That method comprises stopping the 25 ¦ production well, injecting an aqueous solution of polyquaternary amines, injecting an z~a~5~
I ¦ aqueous solution of sc.lle inhibitor, injecting a water flush, shutting in the prod~lction 2 ¦ well, and starting the production well.
3 l 4 ¦ Also novel is the aqueous solution comprising polyquaternary amines andS ¦ scale inhibitors used in the above methods.
6 l 7 ¦ BRIEF DES~RIPTI~N OF THE D~AWINGS
9 ¦ In order to facilitate the understanding of this invention, reference will now be 10 ¦ made to the appended drawings of the preferred embodirnents of thè present invention.
11 ¦ The drawings are exemplary only, and should not be construed as limiting the 12 ¦ invention.
14 ¦ Figure 1 is an ideal scale inhibitor return curve.
16 ¦ Figures 2 and 3 are graphs of results for four different coreflood expeAments.
18 ¦ DETAILED DE~CRIe~lON OF TIIF PR~FERRED EMBODIMENTS
20 ¦ In its broadest aspect, the present invention is a method for prolonging useful 21 ¦ life of scale inhibi~ors injected within a formation. This method involves injecting 22 ~ polyquaternary amines into the formation.
24 ¦ Laboratory experiments show that including a polyquaternary amine solution in 26 ¦ ~he scale i hlbltor squeeze process impro~/es the retention/release charaotoristics of a I
Z~4~
¦ scale inhibitor The squeeze behaves more like the ideal case, showing a longer 2 ¦ squeeze lifetime with the same amount of scale inhibitor.
3 l i 4 ¦ The specific process tested in the laboratory used a preflush of a S ¦ polyquaternary amine solution, followed by a brine flush. This flush removed the bulk 6 ¦ of the amine chemical from the pore spaces, leaving just the polymer adsorbed on the 7 ¦ rock surfaces. This flush was followed with the normal scale inhibitor squeeze 8 ¦ process described above. As detailed below, this new procedure approxirnately 9 ¦ doubled the squeeze lifetime.
13 ¦ The solution of polyquaternary amines can be injected either before or during 14 ¦ the injection of the scale inhibitors. Injecting the polyquaternary amine before the lS ¦ scale inhibitor solution may improve squeeze life more than if injected simultaneously 16 ¦ with a scale inhibitor. On the other hand, injecting the polyquaternary amine 17 ¦ simultaneously with a scale inhibitor requires one less rni7dng tank and is less 18 ¦ complicated to administer.
20 ¦ THE SCALE INHIalTORS
22 ¦ By "scale inhibitors," we mean chemical additives that will prevent the23 ¦ forrnation of water-borne deposits even at low concentrations of additives. Types of 24 ¦ scale inhibitors that would work in the present invention include, but are not lirnited to, 25 1 phosphate esters, phosphonates, and possibly polymeric products such as I
, 4 I
¦The present invention relates to the scale inhibitor squeeze process applied in6 production wells.
8 ¦BAt~KGRouND OF THE INVENTION
10 ¦Scale inhibitors are applied in production wells to prevent precipitation of11 ¦ water-borne deposits, such as barium sulfate, calcium carbonate, and calcium sulfate.
12 ¦ Such precipitates can hinder fluid production by blocking the flow paths either inside 13 ¦ the formation or at the perforations. Scale deposition also can appear in the tubing, 14 ¦ slowing fluid production and damaging downhole equipment.
16 ¦ Qne common method of applying a scale inhibitor is the "squeeze process."
17 ¦ The steps involved in the squeeze process include:
19 ¦1. injecting the aqueous scale inhibitor solution (often a low percent inhibitor 20concentration), 22 ¦2. injecting an overflush brine solution to push the scale inhibitor several feet 23 ¦away from the wellbore, 25 ¦3. shutting-in the well for about a day to allow maximum retention of the 276inhibitor on the rock surfaces, and I I ;~0~ 26~) 2 ¦ 4. putlhlg the well b~ck on normal production.
3 l ¦ The produced water then slowly leaches the retained scale inhibitor from the 5 ¦ formation. Ideally this places a low, but still effective, concentration ~typically a low 6 I mg/l) of the scale inhibitor into the produced water to prevent scale deposition for many weeks or even months.
9 ¦ Figure 1 illustrates the usual return scale inhibitor concentrations from a lo ¦ squeeze treatment. The response from such a treatment often shows:
12 ¦ 1. a short period of no inhibitor while the overflush is produced back;
14 ¦ 2. a rapid increase of inhibitor concentration for a short time, representing 15 ¦ material not retained well in the formation; and 17 ¦ 3. a gradual decline of inhibitor cor.centration.
19 ¦ This continues until the inhibitor concentration finally falls to the rninimum ~0 ¦ effective concentration. The "squeeze lifetime" is the length of time to this point.
21 ¦ Then the squeeze must be repeated.
22 ¦
23 ¦ The squeeze process is chemically inefficient. The inhibitor concentration is 24 ¦ higher than necessary, particularly in the early s~ages, and a significant amount of the 25 ¦ inhibitor often remains adsorbed inside the formation after the squeeze. Usually two-26 ¦ thirds of the injected scale inhibitor is wasted.
~ 5~6 l l 2 I Figure 1 also shows an ideal scale inhibitor return curve. Once the overflush is 3 ¦ brought back, the inhibitor desorbs into the produced water such that the chemical ¦ concentration is just above the minimum effective level. This continues until all 5 ¦ squeezed inhibitor is released from the formation. Such an ideal process would have a 6 ¦ chemical efficiency of almost 100%, or equivalently, a longer squeeze life with the 7 ¦ same amount of scale inhibitor.
8 l 9 ¦ SUMMARY OF TH~ yENTloN
11 ¦ The present invention is a method for prolonging useful life of scale inhibitors 12 ¦ injected within a formation. This method involves injecting an aqueous solution of 13 ¦ polyquaternary amines into the formation. That solution of polyquaternary amines can 14 ¦ be injected either before or with the injection of the scale inhibitors.
16 ¦ Preferably, the scale inhibitors are non-polyrneric scale inhibitors, such as 17 ¦ amine phosphonates. Useful amine phosphonates include aminotri (methylene 18 ¦ phosphonic acid~ and diethyltriatninepenta (methylene phosphonic acid).
20 ¦ Preferably, the polyquaternary amine is either a poly(dimethylamine-co-21 ¦ epichlorohydrin) or a poly(diallyldimethylammonium chloride).
23 ¦ The present invention also involves a method for inhibiting scale buildup within 24 ¦ a formation surrounding a production well. That method comprises stopping the 25 ¦ production well, injecting an aqueous solution of polyquaternary amines, injecting an z~a~5~
I ¦ aqueous solution of sc.lle inhibitor, injecting a water flush, shutting in the prod~lction 2 ¦ well, and starting the production well.
3 l 4 ¦ Also novel is the aqueous solution comprising polyquaternary amines andS ¦ scale inhibitors used in the above methods.
6 l 7 ¦ BRIEF DES~RIPTI~N OF THE D~AWINGS
9 ¦ In order to facilitate the understanding of this invention, reference will now be 10 ¦ made to the appended drawings of the preferred embodirnents of thè present invention.
11 ¦ The drawings are exemplary only, and should not be construed as limiting the 12 ¦ invention.
14 ¦ Figure 1 is an ideal scale inhibitor return curve.
16 ¦ Figures 2 and 3 are graphs of results for four different coreflood expeAments.
18 ¦ DETAILED DE~CRIe~lON OF TIIF PR~FERRED EMBODIMENTS
20 ¦ In its broadest aspect, the present invention is a method for prolonging useful 21 ¦ life of scale inhibi~ors injected within a formation. This method involves injecting 22 ~ polyquaternary amines into the formation.
24 ¦ Laboratory experiments show that including a polyquaternary amine solution in 26 ¦ ~he scale i hlbltor squeeze process impro~/es the retention/release charaotoristics of a I
Z~4~
¦ scale inhibitor The squeeze behaves more like the ideal case, showing a longer 2 ¦ squeeze lifetime with the same amount of scale inhibitor.
3 l i 4 ¦ The specific process tested in the laboratory used a preflush of a S ¦ polyquaternary amine solution, followed by a brine flush. This flush removed the bulk 6 ¦ of the amine chemical from the pore spaces, leaving just the polymer adsorbed on the 7 ¦ rock surfaces. This flush was followed with the normal scale inhibitor squeeze 8 ¦ process described above. As detailed below, this new procedure approxirnately 9 ¦ doubled the squeeze lifetime.
13 ¦ The solution of polyquaternary amines can be injected either before or during 14 ¦ the injection of the scale inhibitors. Injecting the polyquaternary amine before the lS ¦ scale inhibitor solution may improve squeeze life more than if injected simultaneously 16 ¦ with a scale inhibitor. On the other hand, injecting the polyquaternary amine 17 ¦ simultaneously with a scale inhibitor requires one less rni7dng tank and is less 18 ¦ complicated to administer.
20 ¦ THE SCALE INHIalTORS
22 ¦ By "scale inhibitors," we mean chemical additives that will prevent the23 ¦ forrnation of water-borne deposits even at low concentrations of additives. Types of 24 ¦ scale inhibitors that would work in the present invention include, but are not lirnited to, 25 1 phosphate esters, phosphonates, and possibly polymeric products such as I
5~
¦ poly~crylates, polyncrly.lmides, and polymaleic acids. Squeeze treatments commonly 3 use phosphonate chemistry.
4 ¦ Preferably, the scale inhibitors are non-polymeric scale inhibitors. More S ¦ preferably, they are amino phosphonates, such as aminotri (methylene phosphonic 6 ¦ acid) or diethyltriaminepenta (methylene phosphonic acid). The chemical formula for 7 ¦ aminotri (methy}ene phosphonic acid) is:
9 1 . Il .
11 ¦ CH2 14 H C/ \CH
15 ¦ O C)H HO ~\O
18 ¦The selection of phosphonate scale inhibitor can be based upon the chemistry 19 ¦ of the water borne deposit. For example, a diethyltriamine (methylene phosphonic 20 acid) inhibitor probably would be preferred to prevent barium sulfate deposition.
232~HE POLYQUATERNARY AMINES
24 ¦By "polyquaternary amine," we mean a polymer containing the following 226 repeat group:
l l 4 R3 F~
6 l 87 R~, R2, R3, and R4 can be any aliphatic or aromatic group.
9 1 Types of polyquaternary amines that would work in the present invention 10 1 include, but are not limited to, poly(dimethylamine-co-epichlorohydrin) or 11 ¦ poly(diallyldimethylammonium chloride). Depending upon the brine and formation 12 1 chemistry, one polyquaternary amine may be more effective than another in extending 13 1 squeeze lifetime. A preferred embodiment is to use polyquate~nary amines with 14 1 molecular weights below 50,000. Higher molecular weight materials may be diffi1cult to 16 inject.
I A METHOD FOR INHIBITING SCAL~
19 ¦ In one embodiment, scale buildup within a formation surrounding a production 20 ¦ well is inhibited by the steps of stopping the production well; injecting into the 21 1 production well an aqueous solution of polyquaternary aminesj an aqueous solution of 22 1 scale inhibitor, and a water flush; shutting in the production well; and starting the l production well.
25 1 By "stopping a production well," we mean halting normal production. After 26 1 production is stopped, any necessary mechanical modifications are perforrned to allow 27 ¦ subsequen~ fluld injection.
.
I
~45~6~
1 ~
2 I By "water flush," we mean an aqueous brine solution that is injected into a 3 ¦ well undergoing a squeeze treatment.
4 l S ¦ By "shutting in a production well," we mean halting fluid injection and allowing ¦ the injected chemicals time to adsorb to the formation rock.
¦ poly~crylates, polyncrly.lmides, and polymaleic acids. Squeeze treatments commonly 3 use phosphonate chemistry.
4 ¦ Preferably, the scale inhibitors are non-polymeric scale inhibitors. More S ¦ preferably, they are amino phosphonates, such as aminotri (methylene phosphonic 6 ¦ acid) or diethyltriaminepenta (methylene phosphonic acid). The chemical formula for 7 ¦ aminotri (methy}ene phosphonic acid) is:
9 1 . Il .
11 ¦ CH2 14 H C/ \CH
15 ¦ O C)H HO ~\O
18 ¦The selection of phosphonate scale inhibitor can be based upon the chemistry 19 ¦ of the water borne deposit. For example, a diethyltriamine (methylene phosphonic 20 acid) inhibitor probably would be preferred to prevent barium sulfate deposition.
232~HE POLYQUATERNARY AMINES
24 ¦By "polyquaternary amine," we mean a polymer containing the following 226 repeat group:
l l 4 R3 F~
6 l 87 R~, R2, R3, and R4 can be any aliphatic or aromatic group.
9 1 Types of polyquaternary amines that would work in the present invention 10 1 include, but are not limited to, poly(dimethylamine-co-epichlorohydrin) or 11 ¦ poly(diallyldimethylammonium chloride). Depending upon the brine and formation 12 1 chemistry, one polyquaternary amine may be more effective than another in extending 13 1 squeeze lifetime. A preferred embodiment is to use polyquate~nary amines with 14 1 molecular weights below 50,000. Higher molecular weight materials may be diffi1cult to 16 inject.
I A METHOD FOR INHIBITING SCAL~
19 ¦ In one embodiment, scale buildup within a formation surrounding a production 20 ¦ well is inhibited by the steps of stopping the production well; injecting into the 21 1 production well an aqueous solution of polyquaternary aminesj an aqueous solution of 22 1 scale inhibitor, and a water flush; shutting in the production well; and starting the l production well.
25 1 By "stopping a production well," we mean halting normal production. After 26 1 production is stopped, any necessary mechanical modifications are perforrned to allow 27 ¦ subsequen~ fluld injection.
.
I
~45~6~
1 ~
2 I By "water flush," we mean an aqueous brine solution that is injected into a 3 ¦ well undergoing a squeeze treatment.
4 l S ¦ By "shutting in a production well," we mean halting fluid injection and allowing ¦ the injected chemicals time to adsorb to the formation rock.
8 ¦ By "starting a production well," we mean resuming the normal production of 9 ¦ fluids.
11 ¦ EXAMPLES
13 ¦ The core used was a l" dia. x 12" long unfired Berea sandstone. A fresh cole.
l4 ¦ was used for each experiment, having approximately 30 ml. pore volume (l?V). The 15 ¦ temperature and pressure were ambient conditions. The brine was 0.75% NaCl and 16 184 mg/l CaCl2-2H20 (50 mg/l Ca) 18 ¦ The squeeze comprised of steps:
20 ¦ l. Clean the core with acetone, toluene, and brine.
22 ¦ 2. Inject polyquaternary an;~ine solution (if included in that test), followed by a 23 ¦ flush. The polyquaternary amine solution was Haliburton's CLASTA II, 24 ¦ 2% in a 2% NH4Cl brine, 2 PV at 0.5 ml/min. The flush was with 2 PV of 25 ¦ Brine, 0.5 l/min.
Z~)~5~
2 3. Inject scale inhibitor solution. The scale inhibitor solution was Monsanto's 4 Dequest 2000, 2% in Brine (0.25 PV at 0.50 rnl./min.).
4. Inject overflush (Brine of 0.5 PV at 0.5 ml./min.).
8 5. Shut-in core for 20-24 hours.
6. Reverse core.
11 ¦ 7. Start injection of Brine at 1.0 ml./min. from other end to mirnic a well 13 returning to production following inhibitor squeeze.
l4 ¦ was used for each experiment, having approximately 30 ml. pore volume (l?V). The 15 ¦ temperature and pressure were ambient conditions. The brine was 0.75% NaCl and 16 184 mg/l CaCl2-2H20 (50 mg/l Ca) 18 ¦ The squeeze comprised of steps:
20 ¦ l. Clean the core with acetone, toluene, and brine.
22 ¦ 2. Inject polyquaternary an;~ine solution (if included in that test), followed by a 23 ¦ flush. The polyquaternary amine solution was Haliburton's CLASTA II, 24 ¦ 2% in a 2% NH4Cl brine, 2 PV at 0.5 ml/min. The flush was with 2 PV of 25 ¦ Brine, 0.5 l/min.
Z~)~5~
2 3. Inject scale inhibitor solution. The scale inhibitor solution was Monsanto's 4 Dequest 2000, 2% in Brine (0.25 PV at 0.50 rnl./min.).
4. Inject overflush (Brine of 0.5 PV at 0.5 ml./min.).
8 5. Shut-in core for 20-24 hours.
6. Reverse core.
11 ¦ 7. Start injection of Brine at 1.0 ml./min. from other end to mirnic a well 13 returning to production following inhibitor squeeze.
14 ¦ 8. Collect effluent samples and measure the scale inhibitor concentration. Plot the chemical concentration versus the pore volumes of produced brine.
17 ¦ The chemical formula for a useful polyquaternary amine is a poly lg ~ (dimethylamine-co-epichlorohydrin):
22; ¦;:H2--CH--CHz~
1 1 2~
2 ¦ It is sold as a clay stabilizer, used to prevent clay swelling and migration and 3 ¦ subsequent forrnation damage. Table I and Figures 2 and 3 summarize the results for 4 ¦ four different coreflood experiments using this polyquaternary amine.
5 l 6 ¦ TABLE I
7 ¦ Squeeze Lifetime-8 ¦ Polyquaternary Injected Cumulative PV of Water 9 ¦ Amine Preflush Scale Inhibitor Produced to Reach 3 mg/l 10 ¦ Core Tnclllded? Solution pH Inhibitor Concentration 11 ¦ A No 7 20 12 ¦ B Yes 7 43 13 ¦ C No 2 105 14 D Yes 2 245 16 These results show using a polyquaternary amine preflush treatrnent improves17 1 the retention/release characteristics of the scale inhibitor. The polyquaternary amine 18 ¦ returns are closer to the ideal behavior depicted in Figure 1. The inhibitor appears 19 1 initially at a lower concentration and persists in the low mg/l useful range for more 20 ¦ pore volumes of production. Using 3 mg/l as a cut-off, the preflush treatment 21 ¦ approximately doubles the squeeze lifetime.
23 ¦ While the present invention has been described with reference to specific 24 ¦ embodiments, this application is intended to cover those various changes and 25 ¦ substitutions which may be made by those skilled in the art without departing from the 26 ¦ spirit and scopo of the appended claims.
17 ¦ The chemical formula for a useful polyquaternary amine is a poly lg ~ (dimethylamine-co-epichlorohydrin):
22; ¦;:H2--CH--CHz~
1 1 2~
2 ¦ It is sold as a clay stabilizer, used to prevent clay swelling and migration and 3 ¦ subsequent forrnation damage. Table I and Figures 2 and 3 summarize the results for 4 ¦ four different coreflood experiments using this polyquaternary amine.
5 l 6 ¦ TABLE I
7 ¦ Squeeze Lifetime-8 ¦ Polyquaternary Injected Cumulative PV of Water 9 ¦ Amine Preflush Scale Inhibitor Produced to Reach 3 mg/l 10 ¦ Core Tnclllded? Solution pH Inhibitor Concentration 11 ¦ A No 7 20 12 ¦ B Yes 7 43 13 ¦ C No 2 105 14 D Yes 2 245 16 These results show using a polyquaternary amine preflush treatrnent improves17 1 the retention/release characteristics of the scale inhibitor. The polyquaternary amine 18 ¦ returns are closer to the ideal behavior depicted in Figure 1. The inhibitor appears 19 1 initially at a lower concentration and persists in the low mg/l useful range for more 20 ¦ pore volumes of production. Using 3 mg/l as a cut-off, the preflush treatment 21 ¦ approximately doubles the squeeze lifetime.
23 ¦ While the present invention has been described with reference to specific 24 ¦ embodiments, this application is intended to cover those various changes and 25 ¦ substitutions which may be made by those skilled in the art without departing from the 26 ¦ spirit and scopo of the appended claims.
Claims (17)
1. A method for prolonging useful life of scale inhibitors injected within a formation comprising injecting an aqueous solution of polyquaternary amines into said formation.
2. A method according to Claim 1 wherein said solution of polyquaternary amines is injected prior to the injection of said scale inhibitors.
3. A method according to Claim 1 wherein said solution of polyquaternary amines is injected simultaneously with said scale inhibitors.
4. A method according to Claim 1 wherein said scale inhibitors are non-polymeric scale inhibitors.
5. A method according to Claim 4 wherein said non-polymeric scale inhibitors are amine phosphonates.
6. A method according to Claim 5 wherein said amine phosphonate is aminotri (methylene phosphonic acid).
7. A method according to Claim 5 wherein said amine phosphonate is diethyltriaminepenta (methylene phosphonic acid).
8. A method according to Claim 1 wherein said polyquaternary amine is a poly(dimethylamine-co-epichlorohydrin).
9. A method according to Claim 1 wherein said polyquaternary amine is a poly(diallyldimethylammonium chloride).
10. A method for inhibiting scale buildup within a hydrocarbon formation surrounding a production well comprising:
(a) stopping said production well;
(b) injecting an aqueous solution of polyquaternary amines into said production well;
(c) injecting an aqueous solution of scale inhibitor into said production well;
(d) injecting a water flush into said production well;
(e) shutting in said production well; and (f) starting said production well.
(a) stopping said production well;
(b) injecting an aqueous solution of polyquaternary amines into said production well;
(c) injecting an aqueous solution of scale inhibitor into said production well;
(d) injecting a water flush into said production well;
(e) shutting in said production well; and (f) starting said production well.
11. An aqueous solution comprising polyquaternary amines and scale inhibitors.
12. An aqueous solution according to Claim 11 wherein said scale inhibitors are non-polymeric scale inhibitors.
13. A solution according to Claim 12 wherein said non-polymeric scale inhibitors are amine phosphonates.
14. A solution according to Claim 13 wherein said amine phosphonate is aminotri (methylene phosphonic acid).
15. A method according to Claim 13 wherein said amine phosphonate is diethyltriaminepenta (methylene phosphonic acid).
16. A method according to Claim 11 wherein said polyquaternary amine is a poly(dimethylamine-co-epichlorohydrin).
17. A method according to Claim 11 wherein said polyquaternary amine is a poly(diallyldimethylammonium chloride).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2045260 CA2045260A1 (en) | 1991-06-21 | 1991-06-21 | Method for prolonging the useful life of scale inhibitors injected within a formation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2045260 CA2045260A1 (en) | 1991-06-21 | 1991-06-21 | Method for prolonging the useful life of scale inhibitors injected within a formation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2045260A1 true CA2045260A1 (en) | 1992-12-22 |
Family
ID=4147889
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2045260 Abandoned CA2045260A1 (en) | 1991-06-21 | 1991-06-21 | Method for prolonging the useful life of scale inhibitors injected within a formation |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2045260A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023205672A1 (en) * | 2022-04-19 | 2023-10-26 | Saudi Arabian Oil Company | Scale inhibitor fluid and method for inhibiting scale formation |
-
1991
- 1991-06-21 CA CA 2045260 patent/CA2045260A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023205672A1 (en) * | 2022-04-19 | 2023-10-26 | Saudi Arabian Oil Company | Scale inhibitor fluid and method for inhibiting scale formation |
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