Solid formulations suitable for oilfield applications

Abstract

The present invention relates to a solid formulation of soap stick type comprising a primary surfactant, at least one binding agent and at least one dispersant that may especially be an amphoteric surfactant, optionally with additives. The present invention also relates to uses of said formulation, especially for oilfield applications, e.g. for gas well deliquification applications.

Claims

1. A process for gas well deliquification, the process comprising preparing a solid formulation comprising a primary surfactant, at least one binding agent, and at least one dispersant, wherein the primary surfactant is an amphoteric surfactant; the dispersant is a polymeric surfactant chosen from the group consisting of: hyperbranched polymers, poly fatty acid esters, ethylene oxide block copolymers of poly fatty acid, polymers based on polyisobutylene succinic anhydride and mixtures thereof; and wherein the preparing step comprises adding the primary surfactant to a molten composition comprising the binding agent and the dispersant, and injecting the solid formulation into a gas well.

2. The process of claim 1, wherein the primary surfactant is selected from the group consisting of: alkyl amidopropyl sultaines, (C8-C18)alkyl amidopropyl betaines, alkyl amphohydroxypropyl sulfonates, alkyl ampho(di)acetates, and mixtures thereof.

3. The process of claim 2, wherein the primary surfactant is selected from the group consisting of (C8-C18) alkyl amidopropyl betaines.

4. The process of claim 3, wherein the primary surfactant is or contains lauramidopropyl betaine.

5. The process of claim 1, wherein the binding agent is selected from the group consisting of: C16-C24 fatty alcohols, C16-C24 fatty alcohol ethoxylates, fatty acid alkanolamides, fatty acids, natural waxes and resins, high molecular weight polyethylene glycols, polyethylene waxes, mineral and petrolatum waxes, microcrystalline waxes, and mixtures thereof.

6. The process of claim 1, wherein the molten composition further comprises a weighting agent selected from the group consisting of: barium sulphate, sodium sulfate, calcium carbonate, dolomite, water-soluble salts of alkali metals, and mixtures thereof.

7. The process of claim 1, wherein the molten composition further comprises a secondary surfactant that is different from the primary surfactant and is selected from the group consisting of: amphoteric, anionic, cationic and non-ionic surfactants.

8. The process of claim 7, wherein the secondary surfactant is an amphoteric surfactant selected from the group consisting of: alkyl amidopropyl sultaines, (C8-C18)alkyl amidopropyl betaines, alkyl amphohydroxypropyl sulfonates, alkyl ampho(di)acetates, and mixtures thereof.

9. The process of claim 7, wherein the secondary surfactant is an anionic surfactant selected from the group consisting of: acyl taurates, acyl sarcosinates, alkyl ether carboxylic acids, alkyl or alkyl ether phosphate esters, fatty acid isethionates, acyl glutamates, fatty acids, lecithins, linear alkyl benzene sulfonates, α-olefin sulfonates, and mixtures thereof.

10. The process of claim 7, wherein the secondary surfactant is a non-ionic surfactant selected from the group consisting of: fatty acid (C12-C18)alkanolamides, alkyl ethoxylates, sorbitan esters, glyceryl fatty acid esters, glycol fatty acid esters, alkyl polyglucosides, and mixtures thereof.

11. The process of claim 1, wherein the molten composition further comprises a chelating agent selected from the group consisting of citrates and iminosuccinates.

12. The process of claim 1, wherein the molten composition further comprises an antioxidant selected from the group consisting of vegetable waxes and natural soap bases.

13. The process of claim 12, wherein the molten composition further comprises an antioxidant selected from the group consisting of butylated hydroxy anisole, butylated hydroxy toluene, tertiary butyl hydroxyquinone, gallic acid esters, pentaerythrityl tetra-di-t-butyl hydroxyhydrocinnamate, and mixtures thereof.

14. The process of claim 1, wherein the molten composition further comprises an active ingredient selected from the group consisting of: scale inhibitors, halite inhibitors, corrosion inhibitors, biocides, and mixture thereof.

15. The process of claim 14, wherein the scale inhibitor is suitable for oilfield applications and is selected from the group consisting of polycarboxylates phosphonates, polysulfonates and its copolymers, succinates, citrates and end capped vinyl copolymers; wherein the halite inhibitor is suitable for oilfield applications and is selected from the group consisting of hexacyanoferrates, nitrilotrialkanamides and sulfonates polycarboxylate copolymers; wherein the corrosion inhibitor is selected from the group consisting of phosphate esters; and wherein the biocide is THPS.

16. The process of claim 1, wherein the process comprises: preparing the molten composition comprising the binding agent and the dispersant; adding the primary surfactant to said molten composition, in order to obtain a molten formulation; mixing said formulation and pouring it into molds; and allowing the formulation to set at ambient temperature.

Description

EXAMPLES

(1) I—Preparation of Solid Formulations

(2) 10 solid formulations (A to J) were prepared and the compositions of these foam stick formulations are given in the following tables.

(3) TABLE-US-00004 Formulations A B Component (% w/w) (% w/w) MACKAMIDE LMA ex Rhodia 27 19.5 (binding agent) PLURIOL E 1500 (PEG 1500 ex BASF) — — (binding agent) PLURIOL E 4000 (PEG 4000 ex BASF) — — (binding agent) Rapeseed wax (melting point ~65° C., 4.2 5.6 ex Kerax, PothHille) (binding agent/mould release agent) HYPERMER LP1 ex Croda Chemicals 2.8 3.7 (Polymeric dispersant) ALKAMULS S85 ex Rhodia (wetting agent) 1.2 2.2 MACKAM 1200 (85%) ex Rhodia 60 54.7 (primary surfactant) BAYPURE CX-100 (chelant/scale inhibitor) 4.8 3.4 Tetrasodium iminosuccinate ex Lanxess Anhydrous sodium sulphate — 10.9 (weighting agent) Specific Gravity (Calculated) 0.8 0.96 Formulations C D E Component (% w/w) (% w/w) (% w/w) MACKAMIDE LMA ex Rhodia — 21.4 22 (binding agent) TETRONIC RED 9040 ex BASF 2.4 — — (dispersant and demulsifier) PEG-150 Distearate, CUTINA DP S6 (ex 5 — — Cognis) (wetting agent) PLURIOL E 1500 (PEG 1500 ex BASF) 35.1 — — (binding agent) PLURIOL E 4000 (PEG 4000 ex BASF) 6.5 — — (binding agent) HOSTAPUR OSB (C13-15 α-olefin — 12.2 3.8 sulfonate powder (90%), ex Clariant) Rapeseed wax (melting point ~65° C., ex 3.2 4.4 3.8 Kerax, PothHille) (binding/mould release agent) HYPERMER LP1, ex Croda Chemicals — 3.2 2.8 (Polymeric dispersant) ALKAMULS S85 ex Rhodia (wetting agent) — 1.8 1.5 VOLPO S2 (wetting agent), ex Croda 2.8 — — Chemicals Steareth-2 MACKAM 1200 ex Rhodia 34 47.8 52 (primary surfactant) BAYPURE CX-100 (chelant/scale inhibitor) 5 3.2 4.6 Tetrasodium iminosuccinate, ex Lanxess Anhydrous sodium sulphate 6 6.0 9.5 (weighting agent) Specific Gravity (Calculated) 1.17 0.85 0.9 Formulations F G H Component (% w/w) (% w/w) (% w/w) MACKAMIDE LMA ex Rhodia 20 21 20.5 (binding agent) PEG 4000, e.g. PLURIOL E 4000 (ex BASF) 4.0 3.1 4.9 (binding agent) Rapeseed wax (melting point ~65° C.), e.g. 4.7 3.8 3.9 (ex Kerax, PothHille) (binding/mould release agent) HYPERMER LP1, ex Croda Chemicals 3.2 2.8 3 (Polymeric dispersant) ALKAMULS S85 ex Rhodia (wetting agent) 1.1 0.9 1.1 HOSTAPUR OSB ex Clariant 1.1 — — C13-15 α-olefin sulfonate powder (90%), , CRODASINIC LS95 ex Croda Chemicals — 0.9 — Sodium Lauroyl Sarcosinate (94%). GERAPON T42LQ ex Rhodia, — — 3.9 MACKAM 1200 ex Rhodia (80%) 47.1 52.4 46.0 (primary surfactant), BAYPURE CX-100 (chelant/scale inhibitor) 2.3 1.8 2.1 Tetrasodium iminosuccinate, ex Lanxess Anhydrous sodium sulphate 16.5 13.3 14.6 (weighting agent) Specific Gravity (Calculated) 0.7 1.02 1.04 Formulations I J Component (% w/w) (% w/w) MACKAM 1200 ex Rhodia (80%) 54.95 57 (primary surfactant), ALKAMULS S85 ex Rhodia (wetting agent) 1.0 — RHODASURF ON870/E ex Rhodia — 5.0 (binding agent) PEG-150 Distearate, e.g. CUTINA DP S6 — 5.0 (ex Cognis) (wetting agent) Soy Lecithin powder (90% active), ex Camida (co-surfactant) 2.0 — HYPERMER LP1, ex Croda Chemicals (Polymeric dispersant) 4.0 — HYPERMER B261 Poly Fatty Acid — 4.0 EO block copolymer, ex Croda Chemicals (dispersant) BAYPURE CX-100 (chelant/scale inhibitor) 2.0 2.0 Tetrasodium iminosuccinate, ex Lanxess Rapeseed wax (melting point ~65° C., ex 24 — Kerax, PothHille) (binding/mould release agent) PLURIOL E 1500 (PEG 1500 ex BASF) — 22 (binding agent) Anhydrous sodium sulphate (100%) 12.0 5.0 (weigthing agent) Tocopherol acetate, ex Merck KGaA 0.05 — (preservative) Specific Gravity (Calculated) ~1.05 ~1.1

(4) The specific gravity of the stick was estimated from the diameter of the spherical mould and weighing the stick.

(5) Volume (half-sphere)= 1/12 π d.sup.3, where d is the diameter of the mould.

(6) $\mathrm{Density}\left(\mathrm{stick}\right)=\frac{\mathrm{weight}\mathrm{of}\mathrm{stick}\left(g\right)}{\mathrm{volume}}$$\mathrm{Specific}\mathrm{gravity}=\frac{\mathrm{density}\mathrm{of}\mathrm{stick}}{\mathrm{density}\mathrm{of}\mathrm{water}}$

(7) II—Dynamic Foam Tests

(8) A—Methods

(9) The liquid unloading performance of the formulations was assessed using a dynamic foam test apparatus (based on the Bikerman method (R J Pugh, Handbook of Applied Surface and Colloid Chemistry, Volume 2, Eds K Holmberg, D O Shah, M J Schwager, J Wiley & Sons (2002), Chapter 8) and ASTM 892 test).

(10) A 50/50 v/v model brine and condensate (10% w/w sodium chloride and Isopar M (C11-15 iso-paraffins)) was heated to 80° C. in a 1000 ml, 6.0 cm jacketed glass column fitted with a foam generator and condenser to cool the liquid overflow recovered from the column. The fluid was collected in a 1000 ml graduated measuring cylinder. The mixture (˜260 ml) was agitated by injecting nitrogen gas into the fluid at a low rate (less than 0.5 Litres/min) to heat the mixture to the test temperature. A 10% active solution (20 ml) of the solid foam stick in deionised water was prepared in sample vials. The solutions were stored at 80° C. until the formulation had completely dispersed. The foamer solution (1% active solution) was then added drop wise to the mixture in the dynamic foam test apparatus and allowed to disperse. The concentration of surfactant was equivalent to 1000 ppm in the test solution.

(11) The gas flow rate was 1.0 Litres/min and the foam generated was allowed to overflow from the column into the measuring cylinder for 15 minutes. The weight of fluid collected was measured and it was then possible to calculate the liquid unloading efficiency. The volume of the recovered liquids (brine and condensate) was measured in order to determine whether the surfactants posed any risk of forming an emulsion.

(12) B—Results

(13) 1. Liquid Unloading Performance

(14) Liquid unloading performance of the foam sticks of the present invention was benchmarked against Mackam® DAB (lauramidopropyl betaine, amphoteric surfactant, Rhodia). The efficiencies were calculated from the amount of fluid recovered from the column.

(15) $\mathrm{Liquid}\mathrm{Unloading}\left(\%\right)=\frac{\mathrm{Weight}\mathrm{of}\mathrm{fluid}\mathrm{recovered}\mathrm{from}\mathrm{the}\mathrm{column}\times 100}{\mathrm{Total}\mathrm{weight}\mathrm{of}\mathrm{fluid}\left(\mathrm{brine}+\mathrm{condensate}\right)}$

(16) The results of the dynamic foam tests are given in the following table.

(17) TABLE-US-00005 Formulations Parameter Control A B C E F G H Liquid 244.8 242.4 242.3 243.5 242.9 242.6 241.8 243.1 total (g) Liquid 169.1 113.4 139.4 135.8 130.8 115.2 134.5 61.9 recovered (g) Liquid 70 46.8 57.5 55.8 53.9 47.5 55.6 25.5 unloading (%)

(18) The amount of condensate (% v/v) recovered from the column can be estimated from:

(19) $\mathrm{Condensate}\mathrm{recovered}\left(\%\right)=\frac{\mathrm{Condensate}\mathrm{volume}\times 100}{\mathrm{Liquid}\mathrm{recovered}\left(\mathrm{total}\right)}$

(20) The results of the dynamic foam tests are given in the following table.

(21) TABLE-US-00006 Formulations Parameter Control A B C E F G H Liquid 194 124 166 156 158 138 160 74 recovered total (ml) Condensate 110 80 86 98 108 90 104 39 (ml) Condensate 56.7 64.5 51.8 62.8 68.4 65.2 65 52.7 (% v/v)

(22) The liquid unloading efficiencies (w/w (%)) of the formulations were found to be slightly lower than those solely obtained with the betaine. This was not unexpected as the level of amphoteric surfactant present in the test solutions was much lower for the soap sticks compared to the control.

(23) Furthermore, the soap sticks which yielded lower liquid unloading efficiencies (Formulations A, F and H) were found to recover a higher level of condensate, a valuable revenue stream, compared to the control. This is advantageous as the volume of discharge water produced after separation of the condensate is reduced.

(24) 2. Emulsification Potential

(25) The emulsification risk posed by the soap sticks was assessed by measuring the volume of the emulsion formed at the interface between the brine and the model condensate.

(26) $\mathrm{Emulsion}\left(\%v/v\right)=\frac{\mathrm{Emulsion}\mathrm{layer}\times 100}{\mathrm{Volume}\mathrm{of}\mathrm{liquid}\mathrm{recovered}}$

(27) The results of the dynamic foam tests are given in the following table.

(28) TABLE-US-00007 Formulations Parameter Control A B C E F G H Liquid 194 124 166 156 158 138 160 74 total (ml) Interface 4 2 14 0.5 1 1 4 5 layer (ml) Emulsion 2.1 1.6 8.4 0.3 0.6 0.7 2.5 6.8 (%)

(29) Several formulations were observed to pose a potential emulsification risk owing to the presence of an anionic surfactant. In such an embodiment, a demulsifier (nonionic surfactant) is added to the soap stick to facilitate the separation of the hydrocarbons from the recovered fluids. This was illustrated by the PEG formulation (Formulation C) which contained a demulsifier and only produced a trace amount of emulsion (<0.5% v/v of the recovered fluid). The alkanolamides used as the structurant increased the activity of the soap stick and was primarily used as a foam stabiliser. The surfactant improves foam stability by forming a packed monolayer at the gas liquid interface with the amphoteric and retards the drainage of fluid from the liquid lamellae by increasing the surface viscosity.

(30) III—Dissolution Tests

(31) A—Methods

(32) A test was devised to evaluate the dissolution properties of the formulation. A 5% NaCl solution (pH˜7) was heated to 80° C. and the soap stick added to the brine. The amount of soap stick added to the solution was equivalent to 1000-5000 ppm active surfactant when the solid had completely dissolved. The solution was stirred at a low agitation rate (150 rpm) and the time taken for the formulation to dissolve or disperse was noted. The pH of the solution was also measured to determine whether the formulation will change the brine chemistry (scale problems).

(33) The specific gravity of the stick was important because low density solids tended to float on the surface of the brine solution and took longer to disperse.

(34) B—Results

(35) The results of the dissolution tests to obtain a 5000 ppm active dispersion in 5% w/w NaCl at 80° C. are given in the following table for selected formulations.

(36) TABLE-US-00008 Parameter A B C E F H Dissolution time 120 120 15* 95 120 90 (minutes) pH (100%) 8.83 7.53   8.52 7.08 N/A 6.4 *Formulation was molten at 80° C. and therefore indicates a higher melting point wax is required to ensure the formulation does not soften or congeal on storage at elevated temperatures. Slight risk soap stick would probably melt before it reached the perforations.