Experimental Study On Fracturing Fluids Microcosmic Damage With Nuclear Magnetic Resonance

Hydraulic pressure stimulation ( Fracturing ) of oil and gas well is the main method of stimulation . Fracturing is twofold: one is getting the good conductance crack, ameliorating the oil and gas channel; the other is that fracturing fluids will bring damage to the stratum. So, ensuring fracturing's ability of fracturing and taking sands, how to reduce the damage is the important task in the study of fracturing fluids. In this paper, the mechanism of fracturing fluid microcosmic damage is summarized ; and the experiment study of fracturing fluid microcosmic damage to stratum in ChangQing compact stratum is performed using the NMR technology. A new and all-around method is provided for studying the fracturing fluid damage.In this study, firstly thinking about the needs of experiment the temperature control system of the NMR analyzer is improved; then the applied effect of the temperature control system and the instrument is validated. The study of fracturing fluid microcosmic damage include mainly three fields: the appraisement of the damaging rate of permeability; the analysis of the mobile estate of the fracturing fluid and stratum water in the core; the analysis of the mobile nature of the fracturing fluid in the oiliness core. Based on the quantificational test of the fracturing fluid's mobile nature using the NMR and combined with the conventionality test to the damaging rate of permeability due to the fracturing fluid, the main damage mechanism, the damaging degree and the damage laws of the damaging of permeability is studied and analyzed.The result of the study indicates that the improved temperature control system can actualize A/D without buying the special chip. The system have the ability of getting PID parameter itself based on the limit loop theory. The view temperature is 0.01 ℃,and the control precision is 0.1℃. This mach the analyzer's for temperature field. Through a lot of experiment, it is indicated that the temperature control system and the analyzer work stably. The test result is right and the stability and repetition of sample testing get the goal.Experiment study of fracturing fluids microcosmic damage with nuclear magnetic resonance in ChangQing compact stratum attest that the damage rate of permeability because of active water is 10%, mainly the clunch sopping. After fracturing fluidsjostling into the core, the damage rate of permeability owing to active water is 10%. Fracturing fluids has the excess damage rate (30%~40%) compared with the active water. That is on account of high polymer's adsorption and retention. It is the main damage mechanism. The core's damage rate with low permeability is higher than the core with high permeability generally. In ChangQing compact stratum the damage rate of permeability due to clunch sopping, dilating and Jamin's effect is low. The damage rate of permeability because of high polymer's adsorption and retention is high. It is the main damage mechanism.