Research On Fracturing Technology Of Shale Gas Horizonal Well

The shale gas reserves is large in China, but shale gas reservoirs have some characteristics such as low porosity, low permeability, high reservoir stress, low productivity after perforation. Moreover, a vertical well has a bit high productivity after large-scale fracturing, but its production declines too quickly in the pre-production stage to achieve the effective and economic development of hydrocarbon gases.First, this paper describes some features of shale gas reservoirs, such as a large number of nature fractures, high brittle minerals content, and small horizontal stress coefficient difference. Second, based on these features, complex fracture network can develop by large-scale quick water fracturing. Then according to the reservoir characteristics of the stress field and nature fractures, the paper studies the formation mechanism of network fractures, the technological measures, the setting and migration mode of proppant, and the seepage rule of shale gas before and after fracturing, and the stimulation mechanism of shale gas reservoir fracturing has been figured out. Based on the reservoir characteristics, a kind of quick water fracturing fluid system is formed by selecting the drag reducers, the clay stabilizers, and surfactants and comprehensively evaluating the damage of fracturing fluids on reservoirs and drag reduction property. In addition, the low-density fracturing proppant with the size of70/100ym and40/70ym is selected to meet the demand for the sand-carrying ability of quick water fracturing fluids and the setting of proppant to form the effective fractures. Moreover, the technology of quick water fracturing and staged fracturing in horizontal wells is formed by setting the standard for layers selection, complete and perfect perforating optimization, fracture parameters optimization in horizontal wells, and small-scale fracturing test. Finally, fracturing test, analysis on net pressure matching, and microseismic monitoring on ground surface and in underground, the effect is evaluated and analyzed after fracturing. And the study results can be used to guide the design and construction of fracturing.