ABSTRACT

The parameters influencing the geometry of a hydraulic fracture are divided into three categories:

  1. those upon which there is no control, such as Young's modulus and Poisson's ratio of the formation, far-field stress and the reservoir pressure,

  2. those which are easily controlled such as treatment-fluid viscosity and time and

  3. those which are partially changeable, like fluid leak-off and injection rate.

In this paper a study is made of the effects of each individual parameter on the geometry of a hydraulic fracture. Based on the findings reported here, it is concluded that at the present time the treatment-fluid viscosity appears to be the most promising factor for influencing the geometry. Increasing the viscosity has two effects. Directly, it increases the width of the generated fracture, thus yielding better conditions for the transportation of the propping agents. Indirectly, it reduces the volume of fluid lost as leak-off.

Another important conclusion of the paper is that the computed fracture geometries are, to a large degree, influenced by the assumed value of the fracture height. A "reasonable" geometry can be obtained only if one assumes a "reasonable" value for the fracture height.

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