Compositions and methods for treating unconventional subterranean formations

Abstract

Described herein are compositions and methods treating an unconventional subterranean formation with a fluid. These methods can comprise (a) combining a single-phase liquid surfactant package comprising a primary surfactant with an aqueous-based injection fluid to form a low particle size injection fluid, wherein the primary surfactant comprises an anionic surfactant or a non-ionic surfactant; (b) injecting the low particle size injection fluid into a primary wellbore in fluid communication with the unconventional formation; (c) allowing the low particle size injection fluid to contact the unconventional subterranean formation for a period of time; and (d) producing fluid from the unconventional subterranean formation through one or more secondary wellbores in fluid communication with the primary wellbore, wherein the low particle size injection fluid has a maximum particle size of less than 0.1 micrometers in diameter in particle size distribution measurements performed at a temperature and salinity of the subterranean formation.

What is claimed is: 
     
         1 . A method for treating an unconventional subterranean formation with a fluid, the method comprising:
 (a) combining a single-phase liquid surfactant package comprising a primary surfactant with an aqueous-based injection fluid to form a low particle size injection fluid, wherein the primary surfactant comprises an anionic surfactant or a non-ionic surfactant;   (b) injecting the low particle size injection fluid into a primary wellbore in fluid communication with the unconventional formation;   (c) allowing the low particle size injection fluid to contact the unconventional subterranean formation for a period of time; and   (d) producing fluid from the unconventional subterranean formation through one or more secondary wellbores in fluid communication with the primary wellbore,   wherein the low particle size injection fluid has a maximum particle size of less than 0.1 micrometers in diameter in particle size distribution measurements performed at a temperature and salinity of the subterranean formation.   
     
     
         2 . The method of  claim 1 , further comprising producing fluid from the unconventional subterranean formation through the primary wellbore after allowing step (c). 
     
     
         3 . The method of  claim 1 , further comprising ceasing injection of the low particle size injection fluid into the primary wellbore before allowing step (c). 
     
     
         4 . The method of  claim 1 , further comprising producing fluid from the unconventional subterranean formation through one or more secondary wellbores in fluid communication with the primary wellbore during the injecting step (b), during the allowing step (c), after a conclusion of the allowing step (c), or any combination thereof. 
     
     
         5 . The method of  claim 4 , further comprising producing fluid from the unconventional subterranean formation through one or more secondary wellbores in fluid communication with the primary wellbore during the injecting step (b), during the allowing step (c), and after a conclusion of the allowing step (c). 
     
     
         6 . The method of  claim 4 , further comprising monitoring the fluid produced through the one or more secondary wellbores. 
     
     
         7 . The method of  claim 6 , wherein monitoring the fluid comprises monitoring the water content of the fluid produced through the one or more secondary wellbores, monitoring for components of the low particle size injection fluid in the fluid produced through the one or more secondary wellbores, monitoring for signs of emulsion and/or foaming in the fluid produced through the one or more secondary wellbores, monitoring for changes in wellhead or bottom-hole production pressure in the one or more secondary wellbores, or any combination thereof. 
     
     
         8 . The method of  claim 7 , wherein upon observing an increase in the water content of the fluid produced through the one or more secondary wellbore, an increase in a concentration of a component of the low particle size injection fluid in the fluid produced through the one or more secondary wellbores, an increase in emulsion and/or foaming in the fluid produced through the one or more secondary wellbores, an increase in wellhead or bottom-hole production pressure in the one or more secondary wellbores, or any combination thereof during the injecting step (b) or during the allowing step (c), the method further comprises temporarily shutting in the one or more secondary wellbores. 
     
     
         9 . The method of  claim 1 , wherein injecting step (b) comprises injecting a volume of the low particle size injection fluid equal to from 10% to 250% of an estimated stimulated reservoir volume (SRV) of the unconventional formation in fluid communication with the primary wellbore. 
     
     
         10 . The method of  claim 1 , wherein the period of time is from one day to 60 days. 
     
     
         11 . The method of  claim 1 , wherein injecting step (b) comprises injecting the low particle size injection fluid at a pressure and flow rate that does not substantially initiate new fracture formation within the unconventional subterranean formation. 
     
     
         12 . The method of  claim 1 , wherein injecting step (b) and allowing step (c) facilitate release of hydrocarbons from pores in the unconventional subterranean formation. 
     
     
         13 . The method of  claim 1 , wherein allowing step (c) comprises contacting the unconventional subterranean formation with the low particle size injection fluid for the period of time. 
     
     
         14 . The method of  claim 1 , wherein the method improves total hydrocarbon recovery from the primary wellbore and the one or more secondary wellbores. 
     
     
         15 . The method of  claim 1 , wherein the injection of the low particle size injection fluid stimulates the unconventional subterranean formation. 
     
     
         16 . The method of  claim 1 , wherein combination of the single-phase liquid surfactant package with the aqueous-based injection fluid lowers the particle size distribution of the aqueous-based injection fluid when measured at the temperature and salinity of the subterranean formation. 
     
     
         17 . The method of  claim 1 , wherein the method further comprises identifying the one or more secondary wellbores in fluid communication with the primary wellbore. 
     
     
         18 . The method of  claim 17 , wherein identifying the one or more secondary wellbores in fluid communication with the primary wellbore comprises
 (i) injecting a tracer into a primary wellbore in fluid communication with the unconventional subterranean formation;   (ii) measuring a tracer response in a plurality of wellbores in geographic proximity to the primary wellbore; and   (iii) using the tracer response to identify the one or more secondary wellbores in fluid communication with the primary wellbore.   
     
     
         19 . The method of  claim 18 , wherein the tracer response comprises tracer mass recovery, rate of tracer recovery, and/or tracer concentration profile in the plurality of wellbores in geographic proximity to the primary wellbore. 
     
     
         20 . The method of  claim 17 , wherein identifying the one or more secondary wellbores in fluid communication with the primary wellbore comprises analysis of fracture driven interactions between wellbores present in fluid communication with the unconventional subterranean formation, a pressure transient analysis, analysis of geological features of the unconventional subterranean formation, or any combination thereof.