Multistep method of waterflooding
Surfactant adsorption can be minimized using the following injection procedure: (1) an aqueous solution of sacrificial inorganic additives (e.g. sodium carbonate and sodium tripolyphosphate) to cover the adsorption sites of the formation, (2) an optional buffer liquid containing a lower concentration of sacrificial inorganic additive to provide an environment chemically compatible with the surfactant solution to follow, (3) an aqueous, saline solution having a salinity of from about one to two percent by weight, the surfactant having a high molecular weight component (e.g. Alconate 80, median molecular weight 418) and a low molecular weight component (e.g. Pyronate 50, median molecular weight 346), (4) an aqueous, less-saline solution of the low molecular weight component to desorb from the formation high molecular weight component adsorbed from the aqueous, saline solution of surfactant and to create a second bank of surfactant, (5) an optional thickening agent (e.g. Kelzan biopolymer) having decreasing concentrations of thickening agents to form a zone of graded viscosity between the viscosity of the oil and that of the flood water to be injected, and (6) flood water.
- Assignee:
- Mobil Oil Corp.
- Patent Number(s):
- US 3437141
- OSTI ID:
- 7299569
- Country of Publication:
- United States
- Language:
- English
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