Research On Temperature-sensitive Slow-release Coagulant

With the continuous reduction of the oil and gas reserves,the main direction of oil and gas exploration will be transformed into deep and complex reservoirs with high temperature and high pressure.Deep and complex reservoirs with high temperature and high pressure are also facing the difficulty of cementing while having excellent recoverable reserves,which is a new challenge for cementing technology.The cementing of deep complex oil and gas reservoirs is faced with complicated problems such as high temperature,high pressure,high acid(part of block),long sealing section and small space gap,in which the lengthening of sealing section puts forward higher requirements for the performance of cement slurry,and the most important thing is the requirement for the thickening time of cement slurry.The long sealing section spans a plurality of formation temperature intervals,and the cement slurry at different temperatures has a different setting time.In order to pump the cement slurry smoothly,the amount of retarder is usually based on the design of the maximum temperature point at the bottom of the well.However,for the temperature of the top long sealing section,the amount of retarder added is excessive,resulting in excessive retardation of the condensation time at the top and bottom of the long sealing section of oil and gas wells,which is also a difficult problem in cementing technology with long sealing section cementing.In this paper,the acid organics Y2 or alcohols organic Y3,which can be stable in cement slurry,is used as microcapsule wall material by using microcapsule technology.The internal accelerating agents is completely coated by using the microcapsule wall material,and the accelerating agents is not contacted during the displacement pumping process of the cement slurry.The internal accelerating agents is released all at once through the temperature stimulation or the alkaline dissolution microcapsule wall of cement slurry,thereby accelerating the hydration reaction of the cement in the top section of long sealing of the oil and gas well,and promoting its rapid coagulation,so as to relieve or solve the problem of super-retarding of the cement slurry at the top of the long sealing section.In this paper,a suitable combination of accelerating agents was based on the initial setting time of cement slurry and the properties of cement slurry,by using quantitative analysis to research the optimum preparation method of two kinds of thermosensitive slow-release accelerating agents.Though microcapsule coverage rate as the standard,the preparation method,ultrasonic intensity,ultrasonic time,emulsifier type,emulsifier addition and shell ratio were investigated,and 6 kinds of variables were investigated.Investigation by using optical microscope,SEM,XRD,infrared spectrum analysis,sodium ion concentration meter,6 speed rotating viscometer,high temperature and high pressure water loss meter and high temperature and pressure thickeneing instrument,the results are as follows:(1)This article optimizes the combination of two accelerators by quantitative analysis,combining the physical and chemical properties of microcapsule wall materials and cement slurry engineering performance,Na2SO4:Na2CO3:Na2SiO3 is the combination of the accelerating agents of 1:2:2 and the combination of Na2CO3:Na2SiO3 as 1:1,which correspond to the acid organic compounds Y2 of the microcapsule wall material and the alcohols organic compounds Y3 respectively.(2)In this paper,based on the n value,k value,API water loss,thickening time and strength of 24h cement,the acid organic Y2 and alcohols Y3 are selected as microcapsule wall materials in the hydrocarbon mixtures Y1,acid organic Y2,alcohols organic matter Y3 and alcohols organic Y4.(3)By quantitative analysis,the best preparation method of microcapsule HS1 for slow-release accelerating agents is spray drying,and,the best formula is 25g acid organic Y2 and 500mL anhydrous ethanol blend.The water bath was heated to 80?,adding 3%of emulsifier R2 was added,and the accelerating agents combination was added at a ratio 3:1 shell ratio,followed by ultrasonic dispersion 40kHz and 600W for 25min;Through structural analysis and qualitative analysis,slow-release accelerating agents microcapsule HS1 particles are homogeneous.It is suitable for the cementing condition of 80?(the depth of the well is 4000m).The chemical composition of the acid organic substance Y2 before and after the shell is not changed;When the amount of the slow-release accelerating agents was 5%,the thickening time of the cement slurry is shortened from 137min to 84min,and the cement stone strength at 50? and 24h increased by 9.64MPa.(4)By quantitative analysis,the best preparation method for the microcapsule HS2 of the slow-release accelerating agents is the extrusion method,the best formula is the blending of 20g alcohol organic Y3 and 500mL deionized water.The water bath was heated to 95?,4%of emulsifier R2 was added,and the accelerating agents combination was added at a ratio of 3:1 shell ratio,followed by ultrasonic dispersion at 40kHz and 600W for 25min;Through the structure analysis and qualitative analysis,the slow-release accelerating agents microcapsule HS2 particles are more dispersed.It is suitable for the cementing conditions at 95 ?(the depth of the well is 5000m).The chemical composition of the alcohols organic substance Y3 before and after the shell formation has not changed.When the amount of slow-release accelerating agents was 5%,the thickening time of the cement slurry was shortened from 108min to 91min,and the cement stone strength at 50? and 24h increased by 7.41MPa.