Evaluating a hydraulic fracture treatment in a wellbore
First Claim
1. A method for evaluating a fracture treatment comprising:
- a) providing a wellbore penetrating a subterranean hydrocarbon-bearing formation, wherein a pressure differential exists between said wellbore and said formation, and further wherein said formation and said wellbore are bounded by a wellbore face of a production or injection interval across which said formation and said wellbore fluid communicate, said formation having at least one fracture formed therein;
b) placing a first fluid seal across a first cross-section of said wellbore at a first point of said wellbore face in said production or injection interval to block fluid flow across said first cross-section;
c) placing a second fluid seal across a second cross-section of said wellbore at a second point of said wellbore face in said production or injection interval spaced a first wellbore distance from said first point to block fluid flow across said second cross-section, wherein said first and second seals define a wellbore chamber bounded by said first and second seals and a segment of said wellbore face positioned between said first and second points;
d) measuring a plurality of pressure values in said wellbore chamber over a period of time to obtain a pressure rate for said wellbore chamber;
e) repeating steps b) through d) at at least one different sequential pair of points in said production or injection interval to define a plurality of wellbore chambers across the length of said production or injection interval in said wellbore; and
f) comparing said pressure rates for said wellbore chambers to determine whether each of said wellbore chambers is in fluid communication with said fracture.
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Abstract
A method is provided for evaluating the quality of a hydraulic fracture treatment performed in a completed wellbore penetrating a subterranean hydrocarbon-bearing formation. The method is initiated by creating a pressure differential or utilizing an existing pressure differential between the wellbore and the formation and placing a lower packer and an upper packer in the wellbore. The lower and upper packers are positioned in the wellbore at or near the bottom of the producing interval to enclose one or more lower perforations within a wellbore chamber sealed to the remainder of the wellbore. Pressure values of the wellbore chamber are measured for a predetermined time period and then the lower and upper packers are repositioned to enclose the next one or more perforations in sequence within a new wellbore chamber. This procedure is repeated until pressure values have been measured in all wellbore chambers enclosing perforations of interest. The pressure values are used to the determine rate of pressure change in each wellbore chamber. By comparing the rates of pressure change of the wellbore chambers, the character and quality of a fracture and/or fracture network at the casing perforations can be evaluated. A relatively high rate of pressure change in a given wellbore chamber is indicative that the one or more casing perforations of the wellbore chamber are in fluid communication with one or more high quality fractures having a high degree of networking and/or vertical connectivity with other casing perforations. A relatively low rate of pressure change in a given wellbore chamber is indicative that the one or more casing perforations of the wellbore chamber are in fluid communication with one or more low quality fractures having little or no networking and/or vertical connectivity.
84 Citations
20 Claims
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1. A method for evaluating a fracture treatment comprising:
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a) providing a wellbore penetrating a subterranean hydrocarbon-bearing formation, wherein a pressure differential exists between said wellbore and said formation, and further wherein said formation and said wellbore are bounded by a wellbore face of a production or injection interval across which said formation and said wellbore fluid communicate, said formation having at least one fracture formed therein; b) placing a first fluid seal across a first cross-section of said wellbore at a first point of said wellbore face in said production or injection interval to block fluid flow across said first cross-section; c) placing a second fluid seal across a second cross-section of said wellbore at a second point of said wellbore face in said production or injection interval spaced a first wellbore distance from said first point to block fluid flow across said second cross-section, wherein said first and second seals define a wellbore chamber bounded by said first and second seals and a segment of said wellbore face positioned between said first and second points; d) measuring a plurality of pressure values in said wellbore chamber over a period of time to obtain a pressure rate for said wellbore chamber; e) repeating steps b) through d) at at least one different sequential pair of points in said production or injection interval to define a plurality of wellbore chambers across the length of said production or injection interval in said wellbore; and f) comparing said pressure rates for said wellbore chambers to determine whether each of said wellbore chambers is in fluid communication with said fracture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for evaluating the degree of fluid communication between a subterranean formation and a wellbore penetrating the formation comprising:
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a) providing a wellbore penetrating a subterranean hydrocarbon-bearing formation and bounding said formation at a wellbore face, wherein said wellbore is segmented into a plurality of wellbore chambers, including a first and a second wellbore chamber, and said wellbore face is segmented into a plurality of wellbore face segments, including a first and a second wellbore face segment, each of said wellbore face segments having a lower bound and an upper bound and each of said wellbore face segments corresponding to one of said wellbore chambers, and further wherein said formation fluid communicates with each said wellbore chamber across said corresponding wellbore face segment and a pressure differential exists between said wellbore and said formation; b) placing a lower fluid seal across a first lower cross-section of said wellbore at said lower bound of said first wellbore face segment to block fluid flow across said first lower cross-section; c) placing an upper fluid seal across a first upper cross-section of said wellbore at said upper bound of said first wellbore face segment to block fluid flow across said second cross-section, wherein said lower and upper seals bound said first wellbore chamber; d) measuring a plurality of first pressure values in said first wellbore chamber over a first time period to obtain a first pressure rate, while maintaining fluid communication between said formation and each of said wellbore chambers across said corresponding wellbore face segments; e) repositioning said lower and upper seals to said lower and upper bounds of said second wellbore face segment, wherein said lower and upper seals bound said second wellbore chamber; f) measuring a plurality of second pressure values in said second wellbore chamber over a second time period to obtain a second pressure rate, while maintaining fluid communication between said formation and each of said wellbore chambers across said corresponding wellbore face segments; and g) comparing said first pressure rate to said second pressure rate. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification