Scope of Application
This technology is applicable for
horizontal wells with completed open hole, casing cementation and screen
completion. For fracturing improvement for oil sheet and horizon modification
near water layer, and transformation of wells with ineffective packer due to
casing changing or broken, this technology has obvious technological
advantages.
Technical Principle
This technology consists of conventional
string drag type hydraulic sand blasting fracturing technology and immovable
string type hydraulic sand blasting fracturing technology.
(1)Conventional string drag type hydraulic
sand blasting fracturing technology
Tool string with blasting gun is put down
by tubing or coiled tubing to complete one stage hydraulic sand blasting
fracturing. After choking and killing, the string is dragged into the next well
section for further construction. Maximum 5 sections can be constructed for one
time.
(2)Immovable string type hydraulic sand
blasting fracturing technology
Hydraulic sand blasting fracturing tools
with sliding sleeve are put down into the well at once. After the completion of
the first stage construction and fracture closure, a ball is thrown into the
well through the wellhead plug valve. After the setting of the ball on ball
seat, the casing gate is open and the second staged fracturing is carried out.
Well sections are fractured successi vely.
Construction Tools
(1)Compositions of conventional string drag
type hydraulic sand blasting tool
(From bottom to top) guiding shoe + screen
+ lower centralizer + blasting gun + upper centralizer + N80 external upset
tubing + deeper pup joint+ N80 external upset tubing + hanger. Steels with N80
grade and above shall be adopted for cross-over. The temperature and pressure
resistance of the technique strings are 149 ℃ and 70 MPa
respectively.
Structure Diagram of Drag Type Hydraulic Jetting Tool
(2)Composition of immovable string type
hydraulic sand blasting tool
Guide head + perforated pipe + non-return
valve(ball diameter Φ22mm) + centralizer + unclosed blasting gun + centralizer +27/8 ″ upset
tubing + centralizer + sliding sleeve type blasting gun + centralizer + 27/8 ″ upset
tubing + 27/8 ″ external upset safety joint + 27/8″ upset tubing +
tubing hanger Immovable string can be divided into 5 fracturing stages. The
temperature and pressure resistance of the technique strings are 149 ℃ and 70 MPa
respectively.
(3)Composition: The sand blasting gun
consists of an unclosed blasting gun assembly at the bottom and a sliding
sleeve type blasting gun on the top. The outer diameter of the blasting gun
body is 108 mm and that of the centralizer is 116 mm. Every blasting gun is
equipped with a 6×φ6.0mm nozzle assembly and the nozzle is arranged spirally in
120 ° . Nozzle is made by materials like diamond, super rigid alloy and
ceramics, etc..
Structure Diagram of Immovable String Type Hydraulic Sand Blasting Tool
Technical Features
⑴ Conventional string drag type hydraulic sand blasting fracturing
technology
① Tools used
in downhole are simple and short in length.
② The outer
diameter of the tools are small.
③ Backwashing
channels are available.
④ The
possibility of string stuck in sand is low.
⑵ Immovable String Type Hydraulic Sand Blasting Fracturing Technology
① No string
moving is required during fracturing construction.
② The outer
diameter of the tools are small.
③ Backwashing
channels are available.
④
Construction is limited by high wellhead pressure and well depth.
Service Ability and Performance
At present, hydraulic jet sand fracturing
technology has become one of the most important fracturing and production
stimulation methods. Currently the company has carried out field construction
on 15 wells at each major oil field in China with a success rate of 100%. The
average stimulation amount for a single well is 625t and the yield increases
significantly.