Volume fracturing and energy replenishing method for low-yield horizontal well in dense oil reservoir

Abstract

The invention provides a volume fracturing and energy replenishing method for a low-yield horizontal well in a dense oil reservoir. A sectional fracturing pipe column is lowered into a first section for refracturing of the horizontal well, and packing between a target transformation well section and other well sections is achieved; plugging removing fluid is squeezed in at a small displacement, and the purpose of cleaning the zone nearby a hole of a shaft, the zone nearby the shaft, the wall of a deep fracture and a microfracture channel is achieved; a large amount of low-friction-drag oil flooding type fracturing fluid is injected at a large displacement; temporary plugging agents at different scales are added, and secondary bridge plugging of the zone nearby the shaft and fracture far ends is achieved; energy replenishing type fracturing fluid carrying a combined-particle-size supporting agent is injected in a pumped mode, and a main support fracture network system is obtained; after fracturing is finished, the well is closed for 1-2 days of diffusion, then backwashing is carried out with open flow, the sectional fracturing pipe column is uplifted to a next section, and sectional volume fracturing repeated transformation and energy replenishing are completed; sand washing is carried out for well completion, and production is restored. In the repeated transformation process, volume fracturing and energy replenishing are integrated, the fluid seepage distance is shortened, and remaining oil in fractures and the well is utilized; deep energy in the oil reservoir is effectively replenished, and the formation pressure level is increased.

Description

technical field [0001] The invention relates to the technical field of oilfield horizontal well measures to increase production, in particular to a method for supplementing energy by volume fracturing of low-yield horizontal wells in tight oil reservoirs. Background technique [0002] The matrix permeability of unconventional reservoirs in the Ordos Basin is low (<1.0×10 -3 um 2 ), the formation pressure coefficient is low (0.8), and the development benefits of conventional vertical well fracturing are poor. With the advancement and large-scale application of horizontal well drilling + staged fracturing technology, the single-well production of this type of reservoir has been greatly increased. The initial production is 8-10 tons, which is 4-5 times that of the surrounding vertical wells. However, with the prolongation of production time, the single-well production of some fracturing wells gradually decreased, decreasing by 20% to 30% in half a year and 30% to 50% in on...

AI Technical Summary

Problems solved by technology

However, with the prolongation of production time, the single-well production of some fracturing wells gradually declines, decreasing by 20% to 30% in half a year and 30% to 50% in one year, and the reservoir pressure maintenance level is less than 80%.

However, if the current five-point or seven-point area well pattern is used to supplement the energy of tight reservoirs, on the one hand, the physical properties of the reservoirs are tight, the displacement system is difficult to establish, and the formation pressure remains low; on the other hand, due to the development of local micro-fractures, The water injection well communicated with the horizontal well and experienced fractured water flooding. Although the production capacity was restored to a certain extent by shutting down the corresponding water injection well, it also faced the problem of no energy supplement.

The combination of the above reasons leads to low production and low efficiency of some horizontal wells in this type of reservoir, which affects the development benefit and ultimate recovery of the reservoir