Preparation And Properties Research Of Temperature Resistant And Salt Tolerance Intelligent Profile Control Gel For Oilfield

Due to the long-term exploitation,many large-scale advantage channels have been formed in the deep of the reservoir.It lead to inefficient and invalid water cycle is serious.The oil production decline and the water cut ratio rise rapidly.Deep profile control technology is one of the most effective ways to improve swept volume of injection fluid and control inefficient circulation.The conventional profile control gel have the problem of weakened crosslinking reaction and low performance which affected the effect of profile control for the formation high temperature(60-90?)and the high salinity(5-15×10⁴mg/L),as well as alkaline environment.The purpose of this paper is to study the super high molecular weight polyacrylamide polymer profile control gel agent,which can plugging the large-scale advantage channels of reservoir with high temperature,high salinity and alkaline environment.It can meet the actual needs of oilfield development.The realization of versatile gel is a hot topic in academic circles.The temperature and salt tolerance of lactic acid and malonic acid complex organic chromium crosslinking gel system was synthesized for the temperature 40-60?and the salinity 5-15×10⁴mg/L environment.n(chromium):n(lactic acid):n(malonic acid)=1:4:4was the optimal ratio.The choice of super high molecular weight 2300 W polyacrylamide increases the temperature and salt tolerance of chromium gel.The viscosity of the gel was more than 10000 m Pa·s when the optimum dosage was 0.30 wt%.In the system,Cr³⁺hydrated to form six coordinated hydrated ions firstly,which formed a double bond bridge ligand through hydrolysis and hydroxyl bridging.It polymerize to form polynuclear hydroxyl bridging ions.The temperature and salt tolerant gel structure formed by polynuclear hydroxyl bridging ions crosslinking with-COO^-in the polyacrylamide chain.The temperature and salt tolerance of phenolic aldehyde gel system was synthesized for the temperature 60-90?and the salinity 5-15×10⁴mg/L environment.The optimum conditions for the synthesis of phenol aldehyde gel system were determined as follows:temperature 90?,reaction time 30 min,mass ratio of n(phenol):n(formaldehyde)=1:3,selection of super high molecular weight 2300 W polyacrylamide to increase the performance of high temperature and salt resistance.The viscosity of the gel was more than 10000 m Pa·s when the optimum dosage was 0.30 wt%.The crosslinking reaction mechanism of high temperature and salt resistance phenolic resin was defined.The-CH₂-NH-CO-formed by the-CH₂OH of 2,6 in the benzene ring of phenolic resin was reacted with-CONH₂in polyacrylamide molecule.And the network structure of gel was formed finnaly.The increase of salinity led to the enhancement of the interaction between carboxylic groups on polymer molecules and metal ions in solution.The increase of temperature accelerated the gelation process,increase the viscosity of the system,and the three-dimensional structure could inhibit the salt effect of temperature on the polymer effectively.Temperature and pH double response intelligent gel system was synthesized from polyamines and polyethylene glycol for the temperature 45-65?and pH value 8-14environment.The viscosity of the gel was more than 100000 m Pa·s,and it could made up with clean water and field sewage water.And the gelling performance was not affected by high speed shear.It was clear that the response mechanism is the interaction of physical crosslinking and chemical crosslinking.Hydrophobic association produced temperature sensitive response and protonation produced pH value response,which was physical crosslinking.The ring opening reaction between secondary amine group and epoxy group in molecular chain result in chemical crosslinking.The gel reaction of the organic chromium gel system exhibited first-order kinetic properties and the gel have two growth modes from two dimensions to one dimension for the temperature 40-60?and the salinity 5-15×10⁴mg/L environment.Temperature and salinity had little effect on the two time growth mode and gel dense dimension of gel.The growth rate of gel two time accelerated with the increase of temperature and salinity,and salinity had a greater impact on the one time growth rate.Organic chromium gel was more suitable for high salinity environment with dynamic stability of salinity reaction.The gel reaction of the phenol aldehyde gel system exhibited first-order kinetic properties and the gel have two growth modes from two dimensions to one dimension for the temperature 60-90?and the salinity5-15×10⁴mg/L environment.Temperature and salinity had little effect on the two time growth mode and gel dense dimension of gel.The growth rate of gel two time accelerated with the increase of temperature and salinity,and salinity reduced the rate of one time growth rate.The salinity could increased the spatial dimension of one time growth,but the density dimension does not change.Phenol aldehyde gel was more suitable for high temperature environment with dynamic stability of temperature reaction.The gel reaction of the temperature and pH double response intelligent gel system exhibited first-order kinetic properties and the gel have two growth modes from three dimensions to one dimension for the temperature 45-60?and the pH value 10-12 environment.Organic chromium gel was more suitable for high salinity environment with dynamic stability of salinity reaction.It had the stability of reaction kinetics.The organic chromium gel could plugging the core effectively for the temperature40-60?and the salinity 5-15×10⁴mg/L environment.The plugging pressure is greater than 5MPa.The phenol aldehyde gel could plugging the core effectively for the temperature60-90?and the salinity 5-15×10⁴mg/L environment.The plugging pressure is greater than 6MPa.The temperature and pH double response intelligent gel could plugging the core effectively for the temperature 60?and the pH value 9-11 environment.The plugging pressure is greater than 10 MPa.The gel plugging effect of large particle gel is better than that of small particle gel(200nm).The size of temperature and pH value double response intelligent gel particles is the decisive factor of plugging effect.Large particle gel(500 nm)had the great ability of plugging the pore and change the pressure balance and water flow path.The migration of gel particles in core pores changed the core pressure distribution,and the average pressure decreased continuously along the axial direction of the core pores,resulted in an increase in pressure difference between the injection well and the production well.It changed the flow path of oil and water.The plugging effect of large particle gel is better than that of small particle gel(200 nm).The plugging pressure of large particle gel is 8%higher than that of small particle gel,and the oil displacement rate is increased by 10%.