engleski

Long-Term Hydraulic Fracture Conductivities Under Extreme Conditions

Proppants for hydraulic fracturing are subjected to very severe conditions of stress, temperature and chemical environment while they are expected to maintain their structural integrity for a period of many years. The performance of these proppants over time at simulated in-situ conditions has been a topic of laboratory investigation for several years, but in many cases the real conditions exceed the capabilities of the laboratory apparatus. In order to determine the proppant behavior under real reservoir conditions, production history and numerous pressure buildup tests of eight fractured wells have been analyzed. The reservoir conditions of these wells are so severe, that it was almost impossible to simulate them in laboratory. The formation temperature is 179-195 oC (354-383 oF), while the reservoir pressure varies between 44.5 and 50.0 MPa (6453-7250 psi). The producing fluid is large gravity (0.825 to 1.047 to air) sour gas (up to 22% CO2 and up to 0.02% H2S), while the producing water is practically deionized. The proppants are high strength zirconium oxide and sintered bauxite, while the amount of injected proppant varies between 100 and 628 tons (2.2E+05 to 1.38E+06 lbm). The net closure stress is in the range of 30 to 50 MPa (4350-7250 psi). The production time of these hydraulically fractured wells varies between five and ten years. Emphasis in this paper is given to the results of production history and pressure buildup tests analysis, as well as to the relationship of calculated fracture conductivity and reservoir conditions over time.

Hydraulic Fracture; Proppant; Conductivity; Pressure-Transient; Analysis

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