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EP-3768797-B1 - ALKYL ALKOXYLATED CARBOXYLATE SALTS AS STEAM FOAM ADDITIVES FOR HEAVY OIL RECOVERY

EP3768797B1EP 3768797 B1EP3768797 B1EP 3768797B1EP-3768797-B1

Inventors

  • NGUYEN, THU
  • ROMMERSKIRCHEN, Renke
  • FERNANDEZ, JORGE

Dates

Publication Date
20260506
Application Date
20190315

Claims (12)

  1. Use of a surfactant as a steam foam additive in heavy oil recovery, wherein said surfactant comprises: an alkyl alkoxylated carboxylate salt, wherein said alkyl alkoxylated carboxylate salt has a molecular structure as shown in [I]: R-O-(AO') n -(AO") m -R'-COO - M + [I] wherein R is a linear or branched alkyl group, having from 16 to 36 carbon atoms, AO' is a propoxy (PO) group, AO" is an EO or a PO group, R' is a methylene or an ethylene or a propylene group, n = 1 − 15 , m = 0 − 15 , m + n ≤ 20 , provided, in the case where both PO and EO groups are present, the PO/EO molar ratio is less than 1, and M + is an alkali metal ion, an alkanol amine ion, an alkyl amine ion, or an ammonium ion.
  2. The use of claim 1, wherein R is a branched alkyl group.
  3. The use of claims 1 or 2, wherein the branched molecules have an average number of 0.3 to 3.5 branches per molecule, and at least one branch is in the 2-alkyl position.
  4. The use of any of claims 1-4 wherein both PO and EO are present.
  5. The use of any of claims 1-4 wherein R is 20 to 26 carbon atoms.
  6. The use of any of claims 1-5wherein M + is an alkali metal ion, an alkanol amine ion, or an ammonium ion.
  7. A method for heavy oil recovery from a subterranean formation that is penetrated by at least one injection well and one production well, comprising: i) injecting into an injection well a mixture of steam and a surfactant, said surfactant comprising an alkyl alkoxylated carboxylate salt, wherein said alkyl alkoxylated carboxylate salt has a molecular structure as shown in [I], R-O-(AO') n -(AO") m -R'-COO - M + [I] wherein R is a linear or branched alkyl group, having from 16 to 36 carbon atoms, AO' is a propoxy (PO) group, AO" is an EO or a PO group, R' is a methylene or an ethylene or a propylene group, n = 1 − 15 , m = 0 − 15 , m + n ≤ 20 , provided, in the case where both PO and EO groups are present, the PO/EO molar ratio is less than 1, and M + is an alkali metal ion, an alkanol amine ion, an alkyl amine ion, or an ammonium ion, ii) increasing the apparent viscosity of the steam, and at the same time lowering the steam mobility, and iii) recovering oil from the subterranean formation.
  8. The method of claim 7, wherein R is a branched alkyl group.
  9. The method of claims 7 or 8, wherein the branched molecules have an average number of 0.3 to 3.5 branches per molecule, and at least one branch is in the 2-alkyl position.
  10. The method of any of claims 7-9, wherein both PO and EO are present.
  11. The method of any of claims 7-10 wherein R is 20 to 26 carbon atoms.
  12. The method of any of claims 7-11 wherein M + is an alkali metal ion, an alkanol amine ion, or an ammonium ion.

Description

FIELD OF THE INVENTION The present invention relates to steam foam additives and method of use thereof for heavy oil recovery and, in particular, relates to surfactants which are thermally stable and decrease the mobility of steam. Specifically, the surfactants comprise primarily alkyl alkoxylated carboxylate salts. BACKGROUND OF THE INVENTION The present invention relates to a foam-forming surfactant and method for improving the recovery of heavy oil from subterranean wells. As more light oil reservoirs have either depleted or reached their economic limit, the percentage of heavy oils in world oil production continues to rise. However, the recovery of heavy oils can be challenging due to their extremely high viscosity at formation temperature and the low permeability of the sand formations (Larter et al., 2006). Conventional technologies for heavy oil recovery, therefore, must apply heat in the process to melt the oils in order to mobilize them for effective recovery. Some technologies use steam as the source of heat. Some generate heat by in-situ combustion or electrical heating (Nasr and Ayodele, 2005; Szasz and Berry Jr., 1963; Alvarez and Han, 2013). Steam injection has been demonstrated as one of the most effective recovery methods for heavy oils by heating the formation, lowering the viscosity of the heavy oils and thus enhancing the flow of the heavy oils toward the production wells. For example, steam-assisted gravity drainage (SAGD) has been the most common method in temperature infused recovery technologies for heavy oils. In this process, steam is injected into the steam-injection well. The steam rises due to buoyancy forces and forms a steam chamber above the well. The heat in the steam chamber softens the oil so it melts and drains into the production well located under the injection well. The oil, along with the condensed water from steam, can be pumped to the surface and separated from water. Modifications to the SAGD process to improve the oil recovery such as solvent-steam injection and convective SAGD have been evaluated (Sood, 2016; Nasr et al., 2003). However, steam injection in the thermal processes such as SAGD, steam drive and cyclic steam has its own problems including steam override and steam channeling, resulting in low oil recovery in low permeability zones (Zhang et al., 2007; Castanier and Brigham, 1991). The steam override occurs when the gravitational force causes the low-density steam to rise to the top of the formation and bypass a significant fraction of initial oil in place in the lower part of the reservoir. Steam channeling is observed when the steam channels through relatively high-permeability zones and displaces oil from that zone while bypassing a significant fraction of oil in lower-permeability zones (Duerksen, 1986; Eson, 1983; Chen et al., 2010). Both phenomena occur due to the low steam viscosity and can result in high cost of steam generation and low oil recovery. It has been demonstrated in prior art literature that surfactants, injected along with steam, create a steam foam flood that improves the steam flood process in heavy oil recovery. The presence of foam creates a barrier that slows the movement of the steam to both upper levels of the formation and towards the production wells, resulting in the distribution of steam to low permeability zones of the reservoir and transfer heat more efficiently to the oil to reduce oil viscosity. In other words, the issues of steam override and channeling can be overcome by an increase in steam apparent viscosity by surfactant foams. As a result, the average residual oil saturation in the reservoir is reduced. Prior art systems described for anionic surfactants focused mostly on sulfonate surfactants as foaming agents for steam EOR processes, at operating temperatures up to 200 °C (Gassmann et al., 1984; Huang et al., 1984; Muijs et al., 1988; Wall, 1989; Cuenca et al., 2014). Some carboxylates were also reported as steam foaming agents at up to 180 °C (Hawkins and Schievelbein, 1986). There is a continued need for enhanced oil recovery techniques from various oil-bearing formations, such as subterranean oil wells as well as tar or oil sands. The further need to perform such recovery methods at elevated temperatures, such as used in steam applications, are well met by the compounds and methods described in the current invention. SUMMARY OF THE INVENTION The present invention has gone beyond the prior art and discovered a group of anionic surfactants, specifically surface active salts of alkyl alkoxylated carboxylates, that demonstrates the thermal stability and generates strong stable foam at up to 250 °C in the presence of oil. The structures of the identified surfactants can be tailored with respect to surfactant hydrophobicity to optimize the transport and thermodynamic properties of the surfactants and foam, in order to target reservoir temperature and salinity. Such tailoring is affected by careful design, taking i