Long-Term Hydraulic-Fracture Conductivities Under Extreme Conditions

Abstract

Summary 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. To determine the proppant behavior under real reservoir conditions, production history and pressure buildup tests of four fractured wells have been analyzed. The reservoir conditions of these wells are so severe, that it was almost impossible to simulate them in the laboratory. The formation temperature is 179 to 195°C [354 to 383°F], while the reservoir pressure varies between 44.5 and 50.0 MPa [6,453 to 7,250 psi]. The producing fluid is large gravity sour gas, while the producing water is practically deionized. The proppants are mainly high-strength zirconium oxide and sintered bauxite that injected amount varies between 164 and 628 tons [3.6E + 05 to 1.38E + 06 lbm]. During the production time of six to eight years, the effective closure stress reached the values in the range of 32 to 51 MPa [4,640 to 7,395 psi].