Altering wettability in subterranean formations

{
  "publication_number": "US11078406B2",
  "country": "US",
  "kind": "B2",
  "title": "Altering wettability in subterranean formations",
  "abstract": "A method of altering wettability of a subterranean formation penetrated by a well is described. A first oxidizer including a persulfate is introduced to the subterranean formation. A second oxidizer including a bromate is introduced to the subterranean formation. The well is shut in for a period of time to allow the first oxidizer and the second oxidizer to alter the wettability of the subterranean formation toward non-wetting of oil and of water.",
  "claims": [
    "1. A method of altering a wettability of a subterranean formation penetrated by a well, the method comprising: introducing a first oxidizer comprising a persulfate to the subterranean formation; introducing a second oxidizer comprising a bromate to the subterranean formation; shutting in the well for a period of time to allow the first oxidizer and the second oxidizer to alter the wettability of the subterranean formation toward non-wetting of oil and of water; and determining that the wettability of the subterranean formation has been altered toward non-wetting of oil and of water by performing a contact angle test on a rock sample obtained from the subterranean formation, wherein the contact angle test comprises: measuring a first contact angle of a first fluid comprising water on a surface of the rock sample; and measuring a second contact angle of a second fluid comprising a hydrocarbon on the surface of the rock sample, wherein determining that the wettability of the subterranean formation has been altered toward non-wetting of oil and of water comprises determining that the first contact angle and the second contact angle are both in a range from about 70° to about 110°.",
    "2. The method of claim 1, comprising mixing the first oxidizer and the second oxidizer before introduction to the subterranean formation.",
    "3. The method of claim 1, comprising introducing a spacer fluid to the subterranean formation after introducing the first oxidizer and before introducing the second oxidizer.",
    "4. The method of claim 1, comprising introducing a spacer fluid to the subterranean formation after introducing the second oxidizer and before introducing the first oxidizer.",
    "5. The method of claim 1, comprising: encapsulating the first oxidizer in a polymer shell or an oil phase; and encapsulating the second oxidizer in a polymer shell or an oil phase.",
    "6. The method of claim 1, comprising suspending the first oxidizer and the second oxidizer in an emulsion, and introducing the first oxidizer and the second oxidizer to the subterranean formation comprises introducing the emulsion to the subterranean formation.",
    "7. The method of claim 6, wherein a continuous phase of the emulsion comprises diesel, solvent, crude oil, or mineral oil.",
    "8. The method of claim 1, comprising fracturing the subterranean formation.",
    "9. The method of claim 1, comprising introducing a proppant to the subterranean formation.",
    "10. The method of claim 9, wherein the proppant is introduced to the subterranean formation with at least one of the first oxidizer or the second oxidizer.",
    "11. The method of claim 10, wherein a concentration of the proppant is at most about 10 pounds per gallon.",
    "12. The method of claim 1, wherein the well is shut in for at least about 30 minutes.",
    "13. The method of claim 1, wherein the first oxidizer is an aqueous solution of the first oxidizer, and a concentration of the persulfate in the aqueous solution of the first oxidizer is at least about 0.04 M.",
    "14. The method of claim 1, wherein the second oxidizer is an aqueous solution of the second oxidizer, and a concentration of the bromate in the aqueous solution of the second oxidizer is at least about 0.01 M.",
    "15. The method of claim 14, comprising introducing a chloride salt to the subterranean formation.",
    "16. The method of claim 15, wherein the chloride salt is introduced as an aqueous solution of the chloride salt to the subterranean formation with at least one of the first oxidizer or the second oxidizer, and a concentration of the chloride salt is at least 0.25 M."
  ],
  "description_excerpt": "This document relates to methods for treating subterranean formations for enhancing hydrocarbon fluid recovery.\n\nUnconventional hydrocarbon reservoirs are reservoirs with trapped hydrocarbons (for example, oil, natural gas, or combinations of them) in which the hydrocarbon mobility is limited. Extraction of hydrocarbons from such reservoirs typically involves increasing the mobility of the hydrocarbons, for example, by hydraulic fracturing. In hydraulic fracturing, a pressurized fracturing fluid (for example, proppants and one or more chemicals in an aqueous or non-aqueous base fluid) is flowed through the hydrocarbon reservoir. The pressure of the fracturing fluid fractures the reservoir rock to increase mobility of the trapped hydrocarbons.\n\nWettability is the tendency of a fluid to spread on or adhere to a solid surface in the presence of other immiscible fluids. Wettability is a property to measure the interaction between fluid and solid surface phases. In the context of oil and gas applications, wettability is the tendency of a reservoir rock surface to preferentially contact a particular fluid in a multi-phase fluid system. In terms of hydrocarbon production, the wettability of a subterranean formation can affect the hydrocarbon extraction process. Altering the wettability of the subterranean formation can impact the rate of hydrocarbon extraction from the subterranean formation.\n\nThis disclosure relates to altering the wettability of a subterranean formation including organic matter (such as kerogen) in order to improve hydrocarbon extraction from the subterranean formation.",
  "cpc": [
    "C09K 8/601",
    "C09K 8/58",
    "C09K 8/64",
    "C09K 8/665",
    "C09K 8/70",
    "C09K 8/80",
    "E21B 43/25"
  ],
  "ipc": [
    "C09K 8/60",
    "C09K 8/70",
    "C09K 8/80",
    "E21B 43/25"
  ],
  "assignees": [
    "Saudi Arabian Oil Co"
  ],
  "inventors": [
    "Katherine Leigh Hull",
    "Mohammed SAYED"
  ],
  "filing_date": "2019-04-25",
  "publication_date": "2021-08-03",
  "grant_date": "2021-08-03",
  "priority_date": "2019-04-25",
  "application_number": "US-201916395059-A",
  "family_id": "71016617",
  "cited_by_count": 12,
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}