Ultra-low Permeability Reservoir Fracturing Fluid Damage Evaluation Of The Mud Shale Experimental Research

Ultra-low permeability mud shale oil and gas reservoirs are one of the important areas in the development of unconventional oil and gas reservoirs in my country.Improving the development level of ultra-low permeability mud shale oil and gas reservoirs and achieving increased production and injection is an important guarantee for the sustainable development of oil and gas.The development of ultra-low permeability shale reservoirs requires the use of hydraulic fracturing reservoir reconstruction technology,so it is necessary to know the damage of fracturing fluid to ultra-low permeability shale reservoirs.In this paper,three block reservoirs of S,G,and C belonging to ultra-low permeability mud shale and four commonly used fracturing fluids(polymer fracturing fluid,clean fracturing fluid,guar gum fracturing fluid,composite clean Fracturing fluid)as the research object,using nuclear magnetic resonance technology,CT scanning technology and scanning electron microscopy to study the water sensitivity/water blocking damage caused by fracturing fluid to ultra-low permeability shale reservoirs and the pore throat of the reservoir Distribution and damage degree of the apparent structure of the rock and damage mechanism.Experimental studies have shown that ultra-low permeability shale reservoirs are weakly damaged by fracturing fluid water sensitivity/water blocking;after the reservoir core is damaged by fracturing fluid soaking,the rock particles are fragmented more obviously,S block and G zone Block reservoirs are prone to multiple fractures along the rock bedding direction;Block C reservoirs are prone to single fractures along the rock bedding direction.At the same time,the damage performance of these four fracturing fluids is evaluated by comparing the experimental results: the fracturing fluid adsorption and retention phenomenon of the polymer fracturing fluid is serious,which will cause the average coordination number of the reservoir core and the average throat length to decrease.It will cause a certain degree of damage to the reservoirs in each block;the dissolution caused by the clean fracturing fluid is serious,which will increase the average coordination number of the reservoir core,which has a greater impact on the reservoir in Block C;guar gum The cementation of rock particles caused by fracturing fluid is serious,which will increase the average throat length of the reservoir core,which has a greater impact on the reservoir in Block S;composite clean fracturing fluid will cause serious fragmentation of reservoir rock particles,And will cause an increase in the average coordination number of the reservoir core,which has a greater impact on the reservoir in Block G.Based on the experiment,this paper establishes an evaluation method for fracturing fluid damage in ultra-low permeability shale reservoirs,which provides a reliable basis for subsequent reservoir reconstruction,and improves production and production of ultra-low permeability shale reservoirs.Reservoir protection has important guiding significance.