Optimization Study On Network Fracture Conductivity Of Muddy Limestone Reservoir

Shulu sunken muddy limestone tight oil reservoirs are features in high burial depth, complex lithology, well developed natural fracture, which is neither similar to Bakken tight oil, nor to Erods and Songliao basin, that made them difficult to development, and need to explore a set of suitable stimulation mode for this reservoir. In view of the above problems, this thesis research direction based on the optimation on network fracture conductivity of muddy limestone reservoir, we have conducted systematic study of fracture network conductivity formation mode, conductivity matching analysis for muddy limestone reservoir. The main research results are summarized as follows:1. Reservoir numerical simulation method was used to optimize the matching relation between fracture network conductivity and reservoir properties. Based on muddy limestone realistic geological model, we find the most optimal half-length of primary fracture and network facture are 180m and 40m,the most optimal conductivity of primary fracture and network fracture are 30μm.cm and 2μm.cm.2. Rotating disk apparatus was used to study acid-rock reaction mechanism of muddy limestone in different acid systems, and obtained acid-rock reaction kinetic parameters and equations at 130℃.3. Focusing on the fracture filling degree, we has studied the leakoff characteristics of full-filling fracture, partly-filling fracture and mixed fracture, and specifying the leakoff laws of different types of fractures. We recognized that it is difficult to achieve non-connected fracture system communication by means of acid dissolution, which need the hydraulic fracture combined with acid dissolution to realize the greatest degree of fracture network.4. Study on muddy limestone etched fracture conductivity and its maintaining ability in different injection rate. Meanwhile, we recognized that Muddy limestone tight oil reservoir should be based on volume stimulation, acid fracturing is just a complementary.5. A method of primary fracture and network fracture conductivity test has been assembled. Study on propped fracture conductivity of muddy limestone under the condition of different fracture widths, different proppant sizes and placement models. We recognized that network fracture (lmm width fracture represents) should adopt 70/100 mesh proppant to combine blockage effect with drain effect. The primary fracture (3mm and 5mm width fracture represents) could packed by two sizes proppant combination model, provides high conductivity and its maintaining ability.