Wells – Processes – Placing fluid into the formation
Reexamination Certificate
1998-06-08
2001-04-17
Lillis, Eileen D. (Department: 3673)
Wells
Processes
Placing fluid into the formation
C166S250100, C166S280100, C166S281000, C166S305100, C073S152510
Reexamination Certificate
active
06216786
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a method for forming a fracture in a viscous oil bearing, subterranean formation and in one of its aspects relates to a method for inducing a tip screen-out (TSO) fracture in a viscous oil formation which includes treating the formation to decrease the viscosity of the oil as part of the fracturing operation.
2. Background
In producing hydrocarbons from unconsolidated or weakly-consolidated formations, the production of sand along with the hydrocarbons has long been a problem. One of the more commonly used techniques for controlling this sand production is to “gravel-pack” the well adjacent the producing formation. However, installing a proper gravel pack in a particular well can be difficult and expensive and, in some cases, may actually decrease the productivity of the well by increasing the “completion skin” (i.e. damage to the near-wellbore caused by drilling and/or completion of the well).
Recently, it has been proposed to control sand production from certain formation through the use of hydraulic fractures alone, e.g. see U.S. Pat. No. 5,497,658, issued Mar. 12, 1996 to Fletcher et al. wherein a specific fracture is induced in a formation to control the production of sand from that formation. The fracture is sized to have the minimum length necessary to alleviate production of sand from the formation even when the formation is produced at higher-than-normal, draw-down pressures.
Another technique which uses hydraulic fracturing for controlling the production of sand from a particular formation is disclosed in “TSO Frac-Packing: Pilot Evaluation to Full-Scale Operations in A Shallow Unconsolidated Heavy Oil Reservoir” , P. H. Putra et al, SPE 37533, Feb. 10-12, 1997, Bakersfield, Calif. In this method, a fracture is initiated and then deliberately “screened-out” at its tip to thereby limit its growth (i.e. its length) away from the wellbore. Once the fracture has experienced a tip screen-out (TSO), the continued injection of the fracturing fluid, which contains resin-coated proppants, now causes the fracture to widen substantially. The well is then shut-in and the resin on the proppants is allowed to set to form an “external gravel pack” for controlling sand production from the fractured formation.
In hydraulic fracturing operations especially those used to control sand production, such as those briefly described above, the fracturing operation must be specifically designed and engineered for the particular formation to be fractured. In order to do this, certain parameters of the formation must be known in advance. One such parameter is the “leak-off rate” for the formation (i.e. the rate at which fluid will “leak-off” from the fracturing slurry into the formation). This leak-off rate is extremely important, especially in designing TSO fracturing operations since the length of the fracture into the formation is controlled by deliberately allowing fluid (i.e. liquid) from the fracturing fluid to leak-out into the formation at the predetermined rate. This allows the fracture to grow to its predicted length before sufficient liquid leaks into the formation whereupon the proppants in the slurry will now form a “sand-bridge” at the tip of the fracture which, in turn, blocks further flow of slurry past that point. Since the length of the fracture can now no longer grow outward from the wellbore, it will be widened instead by the continued injection of fracturing slurry. Once all of the resin-coated proppants have been placed, the resin is allowed to set to form an external gravel pack around the well casing.
One known way for determining the leak-off rate of a formation is a process known as “data-fracturing” (DF). In this process, the formation is first fractured using only the liquid which is to be used in the subsequent fracturing operation. That is, no proppant material is used in the DF operation. An interval of the wellbore adjacent the formation is isolated and the fracturing liquid is injected into the formation to initiate the fracture. The wellbore is then shut-in and the pressure is allowed to decay (i.e. the fracturing fluid leaks-off into the formation allowing the fracture to close). The time it takes for the fracture to close after the well is shut-in is recorded and, as will be understood in the art, provides the data necessary for determining the leak-off rate for that fluid into that formation.
Data-fracturing (DF) operations and the subsequent fracturing operations based on data gathered from DF operations work well where the fractured formation contains light hydrocarbons and/or gas. However, in formations containing viscous hydrocarbons (i.e. oils having a viscosity of above about 17 centipoises), it is difficult, if possible at all, (a) to use DF or similar operations for establishing accurate leak-off rates or (b) to design specific fracturing operations for that formation based on leak-off rates of the fracturing fluid. This is especially true where TSO fracturing operations are to be used to control sand production in viscous formations.
It is believed that the difficulty in obtaining accurate leak-off rates and in designing fracturing operation for viscous oil formations lies in the fact that the viscous oil impedes the flow (i.e. leak-off) of fracturing fluid into the formation. This results in basically useless leak-off rates from standard DF operations and, further actually prevents the fluid from the fracturing slurry from leaking off at the rate necessary to screen-out the proppants during a subsequent TSO fracturing operation. Since such fractures must be precisely engineered to insure good results, it can be seen that the need exists for improving the accuracy of the leak-off data from DF or similar operations and for designing the subsequent fracturing operations when the operations are to be carried out in viscous oil formations.
REFERENCES:
patent: 3330353 (1967-07-01), Flohr
patent: 3349849 (1967-10-01), Closmann
patent: 3378074 (1968-04-01), Kiel
patent: 3552494 (1971-01-01), Kiel
patent: 3601198 (1971-08-01), Ahearn
patent: 3710865 (1973-01-01), Kiel
patent: 3713915 (1973-01-01), Fast
patent: 3730276 (1973-05-01), Land
patent: 3739852 (1973-06-01), Woods et al.
patent: 3822746 (1974-07-01), Gogarty
patent: 3858658 (1975-01-01), Strubhar et al.
patent: 3896877 (1975-07-01), Vogt, Jr. et al.
patent: 4141415 (1979-02-01), Wu et al.
patent: 4217231 (1980-08-01), King
patent: 4393933 (1983-07-01), Nolte et al.
patent: 4398416 (1983-08-01), Nolte
patent: 4509598 (1985-04-01), Earl et al.
patent: 4749038 (1988-06-01), Shelley
patent: 4836280 (1989-06-01), Soliman
patent: 4887671 (1989-12-01), Stevens, Jr.
patent: 4917188 (1990-04-01), Fitzpatrick, Jr.
patent: 5005643 (1991-04-01), Soliman et al.
patent: 5005648 (1991-04-01), Friedman et al.
patent: 5050674 (1991-09-01), Soliman et al.
patent: 5070457 (1991-12-01), Poulsen
patent: 5074359 (1991-12-01), Schmidt
patent: 5143156 (1992-09-01), Bromley
patent: 5207271 (1993-05-01), Sanchez et al.
patent: 5271463 (1993-12-01), Jennings, Jr.
patent: 5305211 (1994-04-01), Soliman
patent: 5421412 (1995-06-01), Kelly et al.
patent: 5437331 (1995-08-01), Gupta et al.
patent: 5441340 (1995-08-01), Cedillo et al.
patent: 5497658 (1996-03-01), Fletcher et al.
patent: 5497831 (1996-03-01), Hainey et al.
patent: 5558161 (1996-09-01), Vitthal et al.
patent: 5595248 (1997-01-01), Scott, III
patent: 5883053 (1999-03-01), Tudor
patent: 5921317 (1999-07-01), Dewprashad et al.
patent: 5948733 (1999-09-01), Cawiezel et al.
patent: 5964295 (1999-10-01), Brown et al.
“Propped Fracturing as a Tool for Sand Control and Reservoir Management”; Bale et al.; SPE24992; Cannes, France; Nov. 16-18, 1992.
TSO Frac-Packing: Pilot Evaluation to Full-Scale Operation in a Shallow Unconsolidated Heavy Oil Reservoir; Putra et al; SPE 37533; Bakersfield, CA. Feb. 10-12, 1997.
A Systematic Approach to Developing Engineering Data for Fracturing Poorly Consolidated Formations; Upchurch et al; SPE 38588; San Antonio, TX; Oct. 5-8, 1997.
Griffin Lawrence G.
Montgomery Carl T.
Atlantic Richfield Company
Faulconer Drude
Lee Jong-Suk
Lillis Eileen D.
LandOfFree
Method for forming a fracture in a viscous oil, subterranean... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for forming a fracture in a viscous oil, subterranean..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for forming a fracture in a viscous oil, subterranean... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2452017