Pitakbunkate, Termpan (2010-08). Incorporating Rigorous Height Determination into Unified Fracture Design. Master's Thesis. Thesis uri icon

abstract

  • Hydraulic fracturing plays an important role in increasing production rate in tight reservoirs. The performance of the reservoir after fracturing can be observed from the productivity index. This parameter is dependent on the fracture geometry; height, length and width. Unified fracture design (UFD) offers a method to determine the fracture dimensions providing the maximum productivity index for a specific proppant amount. Then, in order to achieve the maximum productivity index, the treatment schedules including the amount of liquid and proppant used for each stage must be determined according to the fracture dimensions obtained from the UFD. The proppant number is necessary for determining the fracture geometry using the UFD. This number is used to find the maximum productivity index for a given proppant amount. Then, the dimensionless fracture conductivity index corresponding to the maximum productivity index can be computed. The penetration ration, the fracture length, and the propped fracture width can be computed from the dimensionless fracture conductivity. However, calculating the proppant number used in UFD requires the fracture height as an input. The most convenient way to estimate fracture height to input to the UFD is to assume that the fracture height is restricted by stress contrast between the pay zone and over and under-lying layers. In other words, the fracture height is assumed to be constant, independent of net pressure and equal to the thickness of the layer which has the least minimum principal stress. However, in reality, the fracture may grow out from the target formation and the height of fracture is dependent on the net pressure during the treatment. Therefore, it is necessary to couple determination of the fracture height with determination of the other fracture parameters. In this research, equilibrium height theory is applied to rigorously determine the height of fracture. Solving the problem iteratively, it is possible to incorporate the rigorous fracture height determination into the unified fracture design.
  • Hydraulic fracturing plays an important role in increasing production rate in tight
    reservoirs. The performance of the reservoir after fracturing can be observed from the
    productivity index. This parameter is dependent on the fracture geometry; height, length
    and width.
    Unified fracture design (UFD) offers a method to determine the fracture
    dimensions providing the maximum productivity index for a specific proppant amount.
    Then, in order to achieve the maximum productivity index, the treatment schedules
    including the amount of liquid and proppant used for each stage must be determined
    according to the fracture dimensions obtained from the UFD.
    The proppant number is necessary for determining the fracture geometry using
    the UFD. This number is used to find the maximum productivity index for a given
    proppant amount. Then, the dimensionless fracture conductivity index corresponding to
    the maximum productivity index can be computed. The penetration ration, the fracture
    length, and the propped fracture width can be computed from the dimensionless fracture
    conductivity. However, calculating the proppant number used in UFD requires the fracture height as an input. The most convenient way to estimate fracture height to input
    to the UFD is to assume that the fracture height is restricted by stress contrast between
    the pay zone and over and under-lying layers. In other words, the fracture height is
    assumed to be constant, independent of net pressure and equal to the thickness of the
    layer which has the least minimum principal stress. However, in reality, the fracture may
    grow out from the target formation and the height of fracture is dependent on the net
    pressure during the treatment. Therefore, it is necessary to couple determination of the
    fracture height with determination of the other fracture parameters.
    In this research, equilibrium height theory is applied to rigorously determine the
    height of fracture. Solving the problem iteratively, it is possible to incorporate the
    rigorous fracture height determination into the unified fracture design.

publication date

  • August 2010