Applying fuzzy-ball fluid to the water control fracturing in deep coal-measure tight gas reservoirs in Sulige

The reservoirs of the deep coal-measure tight gas reservoirs in Sulige are thinner, so water layers can be connected easily in the process of fracturing, which leads to water production of gas wells. Therefore, it is necessary to carry out water control while the deep coal-measure tight gas reservoirs are fractured. In this paper, the plugging fuzzy-ball fluid was used for water control fracturing, which can improve the gas production while reducing the water production. Evaluation experiments were conducted on the fuzzy-ball fluid prepared in the laboratory. The fuzzy-ball fluid was mixed with preflush fluid and formation water respectively in the equal volume to test its compatibility. Then, the pressure of gas and water to break through the fuzzy-ball plugged matrix core and fracturing core plunger was measured by using the core displacement device, so as to characterize the ability of fuzzy ball to increase gas production and plug water. It is shown that no settlement is formed after fuzzy-ball fluid is mixed with preflush fluid and formation water respectively and the breakthrough pressure gradient of gas and water is 0.02 MPa/cm and 0.04 MPa/cm respectively in the fracture-containing core plugged with fuzzy-ball fluid and 0.03 MPa/cm and 0.2 MPa/cm respectively in the matrix core plugged with fuzzy-ball fluid, all of which meet the requirements of field construction. Water control fracturing is carried out in Well A and B of Sulige Gas Field. After preflush fluid is injected into both wells for fracturing, 50 m³ fuzzy-ball fluid is pumped to plug water. And compared with the neighboring wells in the same layer, average daily production within 161 days of Well A and B is 13.71% and 6.99% higher respectively after water control fracturing. Foam drainage is carried out 3 times and 63 times respectively in the neighboring wells (C and D), but no liquid loading occurs in Well A and B after they are put into production. In conclusion, applying fuzzy-ball fluid to the water control fracturing in deep coal-measure tight gas reservoirs can realize gas production increase and water production reduction.