Evaluation Of Development Effect And Fracturing Parameter Optimization Of Carboniferous Reservoir In Block D

Based on actual production data,this thesis has completed the well selection procedure for repetitive fracturing by establishing a theoretical model for repetitive fracturing in straight wells,compared the advantages and disadvantages of volumetric fracturing and conventional fracturing by numerical simulation,and established a theoretical method for fracture parameter optimization.Some important conclusions are listed as follows:The well in Block D can maintain continuous production for a long time,indicating that the shallow,low-permeability reservoir has the potential to form a stable seepage field;through fracturing,both straight and horizontal wells can obtain economic production capacity,and the initial daily production of the wells varies greatly,with a distribution within 30 tons,while the average daily production is relatively concentrated,mainly within 5 tons,accounting for 72%.A well selection model for repeated fracturing based on five indexes: dimensionless pore elastic stress redirection quotient,mechanical effect stress redirection quotient,completion quotient,reservoir depletion index,and initial decreasing index was established,and well selection criteria and procedures based on quantified indexes were developed.105 straight wells in the area were systematically analyzed and evaluated for repeated fracturing suitability,and 19 wells with repeated fracturing potential were preferentially selected.Two unfavorable factors in this zone limit the large-scale promotion of repetitive fracturing: first,the formation pressure is low,especially the repetitive fracturing effect is not obvious at low pressure in late production,when the focus is on replenishing formation energy;second,the burial depth in this zone is shallow,and it is difficult to form a steering for repetitive fracturing,resulting in fractures mostly re-fractured near old fractures,which will also limit the promotion of this method to a certain extent.Using numerical simulation technology,we systematically compared the adaptability of multi-stage fracturing simple fractures and volumetric fracture seam network development in the extra-low permeability reservoir in this zone.The analysis shows that the reservoir permeability in this zone can ensure fluid entry into the wellbore under a certain pressure difference,and volumetric fracturing has higher initial production advantages relative to conventional multi-stage fracturing at the same proppant dosage,but conventional long fractures have greater production advantages as production proceeds.It is recommended that conventional fracturing should be the main focus,supplemented by volume fracturing in very low permeability zones.A fracture optimization method was established based on the pumped formation support dosage as a constraint,and proposed different fracturing strategies for reservoirs with different permeability: medium and high permeability reservoirs should be mainly short and wide fractures to ensure the flow channel of the fractures.Low and ultra-low permeability reservoirs should be dominated by narrow and long fractures to ensure that there is enough drainage area to allow fluid to enter the fractures from the formation.Combining production and reservoir physical conditions,fracturing in this area should be based on creating long fractures.