Patent Application
20150316048
Hydraulic fracturing is a process in which a geological formation is fractured by pumping a fracturing fluid at a pressure that exceeds parting pressure of the formation. The fracturing fluid is delivered into a wellbore by specially designed high pressure pumps, commonly referred to as “frac pumps”. As the frac pumps begin operation, injection rate of the fracturing fluid is maintained at the maximum matrix flow capacity causing downhole pressure to increase until a point at which the pressure exceeds a tensile strength of the geological formation. At this point, the geological formation will start to rupture and a fracture will form. The fracture will propagate in a direction ultimately perpendicular to a least principle stress presented in the formation. This process is commonly known as formation breakdown. The injection rate and outlet pressure of the frac pumps is controlled to deliver the fracturing fluid at a fluid pressure that promotes breakdown.
In accordance with an exemplary embodiment, a method of delivering fluids into an underground geological formation to promote geological formation breakdown includes inputting, into a user interface, one or more geological formation parameters, inputting, into the user interface, one or more wellbore parameters, inputting, into the user interface, one or more fluid injection parameters, and calculating a desired breakdown pumping style based on each of the one or more geological formation parameters, one or more wellbore parameters, and one or more fluid injection pumping parameters.
In accordance with another aspect of an exemplary embodiment, a system includes a user interface, a memory, and a central processor unit (CPU), communicatively coupled to the memory and the user interface. The system is configured to perform a method including receiving, into the user interface, one or more geological formation parameters, receiving, into the user interface, one or more wellbore parameters, receiving, into the user interface, one or more fluid injection parameters, and calculating a desired breakdown pumping style based on each of the one or more geological formation parameters, one or more wellbore parameters, and one or more fluid injection parameters.
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
Monitoring and control system 12 is further shown to include a user interface 26 and one or more sensors 30 that send data to controller 14. Controller 14 provides a breakdown pressure style output 34 desirable for a particular formation. Controller 14 also includes a breakdown pressure style adjustment output 40 that accounts for pressure changes in the particular geological formation based on inputs from sensors 30, as will be detailed more fully below. Controller 14 then controls fluid injection rate and fluid pressure through output 42 to establish and/or adjust the breakdown pressure style as will be also discussed more fully below.
Reference will now be made to
After receiving input data, monitoring and control system 12 outputs a recommended breakdown style, in block 62. The recommended breakdown pressure style may include a Rapid Up Breakdown style 70, as shown in
Controller 14 compares data received from sensors 20 with stored threshold values which may be calculated by CPU 16 or manually input, that may be associated with the particular geological formation. The threshold values may include upper and lower fluid injection rate threshold values α1 and α2 and upper and lower injection pressure change over time or dP/dt threshold values δ1 and δ2. If, for example, sensed injection pressure is less than α1 and dP/dt is less than δ1, as determined in block 82, fluid injection rate may be increased in block 84. If for example sensed injection pressure is greater than α1 and less than α2 and dP/dt is greater than δ1 and less than δ2, as determined in block 88, fluid injection rates may be held in block 90. Further, if sensed injection pressure is greater than α2 and dP/dt is greater than δ2, as determined in block 94, fluid injection rate may be decreased in block 96. In this manner, monitoring and control system 12 may adjust fluid injection rate due to changes in the geological formation. Monitoring and control system 12 may also be configured to predict unfavorable conditions which may lead to job execution problems and also avoid other treatment execution issues that could lead to a less than desirable well production.
While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.
