Changes
/* Summary of Slickwater fracturing */
Baker Hughes focused on hydraulic fracturing treatment by using ULW (Ultra lightweight) proppant and low viscosity slick water fracturing fluid. And performing fracturing method in two stages helps in reducing the conductivity damage....[Contd]
==Acid Fracturing==
===Graphical representation of Assignee's holding patents of Acid fracturing===
[[Image:Assignee acid.jpg|center|500px]]
Schlumberger ranks first in acquiring no. of patents in acid fracturing. ExxonMobil acquires 3 patents of acid fracturing whereas Baker Hughes has 2 patents.
'''Table: Acid Fracturing patent of different Companies.'''
{|border="2" cellspacing="0" cellpadding="4" width="80%"
|align = "center" bgcolor = "#9BBB59" colspan = "4"|'''Acid Fracturing'''
|-
|align = "center" bgcolor = "#9BBB59"|'''S.No'''
|align = "center" bgcolor = "#9BBB59"|'''Assignee'''
|align = "center" bgcolor = "#9BBB59"|'''Patent'''
|align = "center" bgcolor = "#9BBB59"|'''Comment'''
|-
|align = "center" bgcolor = "#9BBB59" rowspan = "2"|'''1'''
|align = "center" rowspan = "2"|Schlumberger
|<font color="#0000FF"><u>[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7380602.PN.&OS=PN/7380602&RS=PN/7380602 US7380602B2]</u></font>
|Treating a subterranean carbonate with a fluid comprising of an acid, chelating agent, or betaine surfactant.
|-
|<font color="#0000FF"><u>[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6828280.PN.&OS=PN/6828280&RS=PN/6828280 US6828280B2]</u></font>
|Stimulation of hydrocarbon production from low permeability formations by hydraulic fracturing, acid fracturing, and hydraulic fracturing followed by gravel packing in a single operation
|-
|align = "center" bgcolor = "#9BBB59"|'''2'''
|align = "center"|<nowiki>### </nowiki>
|align = "center"|<nowiki>****</nowiki>
|align = "center"|<nowiki>****</nowiki>
|-
|align = "center" bgcolor = "#9BBB59"|'''3'''
|align = "center"|<nowiki>### </nowiki>
|align = "center"|<nowiki>****</nowiki>
|align = "center"|<nowiki>****</nowiki>
|-
|}
These sections now concentrate on the work done by the companies or institutes.
===Schlumberger===
[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7380602.PN.&OS=PN/7380602&RS=PN/7380602 US7380602B2] titled "Composition and method for treating a subterranean formation" by Schlumberger. Matrix acidizing treatment leads to the problem of (1) inadequate radial penetration (portions of the formation away from the wellbore in the radial direction is untouched by the acid because all of the acid reacts before it can get there); (2) incomplete axial distribution(acid does not reach other parts of the formation along the wellbore where it is actually desired most because the acid begins to dissolve the most reactive or first-contacted material in the wellbore and/or the matrix, so diversion of the acid is required to treat the desired zones); (3) corrosion of the pumping and well bore tubing (4) and iron precipitaion in sour wells
-Acid treatments is susceptible to the temperature of the subterranean formation and the metal corrosion is enhanced at high temperatures
'''Treating a subterranean carbonate with a fluid comprising of an acid, chelating agent, or betaine surfactant''' which is pumped into the subterranean carbonate formation before mixing, called as a self-diverting wormholing acid fluid system or a self-diverting retarded acid fluid system
-Low pH solution of chelating agent pH of less than about 3 and above about 1 and a pH value at which the free acid form of the chelating agent precipitates (i.e. pH above about 1), is made by adding an acid to the chelating agent, the acid gets consumed to partially neutralize the chelating agent and therefore the acid which reduces the pH of the solution of a chelating agent does not react with the formation.
[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6828280.PN.&OS=PN/6828280&RS=PN/6828280 US6828280B2] titled "Methods for stimulating hydrocarbon production" by Schlumberger. In hydraulic and acid fracturing, a first, viscous fluid called a "pad" is typically injected into the formation to initiate and propagate the fracture and often to contribute to fluid loss control and mainly consist of polymers. Hence there is a need of an inexpensive material for the pad so that
a) It creates and propagates a sufficiently wide fracture,
b) Minimize chemical, equipment and hydraulic horsepower expense,
c) Capable of forming a filter cake to control leak-off during the job (not required when acid fracturing with a low viscosity acid) and
d) Degradable to maximize subsequent production.
Methods are provided for stimulation of hydrocarbon production from low permeability formations by hydraulic fracturing, '''acid fracturing''', and hydraulic fracturing followed by gravel packing in a single operation. The methods uses a first injected viscous pad made with a low concentration (such as about 10 to about 15 ppt (pounds per thousand gallons fluid)) of uncross linked polymer and provides an inexpensive and effective material to initiate and propagate the fracture and control fluid loss, followed by a second injected fluid gelled with a viscoelastic surfactant for carrying proppant or acid into the fracture. The viscosity of the uncross linked polymer is lower than that of the VES fluid subsequently pumped, requiring less hydraulic horsepower expense.
