Research And Application Of Novel Profile-Controlling Agent For Hot Water Flooding In Shallow And Thin Reservior Of Heavy Oil Oilfield

This paper focuses on the development and application of a new type of high-temperature profile control agent for shallow and thin heavy oil reservoir.There is difference between water flooding profile control in shallow heavy oil reservoir and conventional reservoir profile control and deep layer heavy oil reservoir water flooding control. This paper is a series of work on the development, synthesis, optimization and application of the profile control agent for thermal recovery of shallow heavy oil reservoirs.The western slope area of Daqing Oilfield is rich in heavy oil reservoir, which is an important support and guarantee for the stable production of Daqing Oilfield. But the heavy oil reservoir is different from the heavy oil reservoir of Liaohe Oilfield and Shengli Oilfield,with the characteristics of shallow buried, thin reservoir and so on. This type of Du66 block due to the reservoir heterogeneity, distributed in normal rhythm, the upper part of the reservoir can not absorb water, while the lower part to absorb water, caused by hot water flooding effect is not balanced, reservoirs can not be effectively utilized, which restricts the heavy oil by hot water flooding development effect. Therefore, it is necessary to study profile control agent of high temperature tolerance, resistance to shear, gelling agents controlled for the block.For lignin (SL), acrylamide (AM), allyl polyethylene glycol (APEG) as raw materials,ammonium persulfate and sodium bisulfite as initiator synthesize copolymer SL-AM-APEG.The optimal synthesis conditions are as follows: the reaction temperature was 90?, monomer concentration 28%, initiator (the best ratio is 2) concentration 0.5%, reaction time 12h. The salinity of synthetic products in 4000-7000mg/L, temperature in 50 to 120?, shear rate in the 1000-5000s-1, pH value between 7-11 changes, viscosity is basically stable, with a certain degree of salt resistance, high temperature resistance, shear resistance, acid and alkali resistance.With SL-AM-APEG as the main agent, cross-linking agent A, cross-linking agent B and stabilizer C as components, a new type of high temperature profile control agent NGW is synthesized. When the salinity of 8000mg/L, the viscosity is still as high as 30000mPa.s.Adding control agent concentration between 0.1% and 0.6%, the gelling time can be controlled between 1-5.5d, strong resistance to salt and gelling time controllable performance.Through the experimental evaluation of temperature resistance, shearing resistance and reservoir adaptability, the NGW profile control agent, the chrome system profile control agent,the compound ion profile control agent and the resin profile control agent are optimized. The results show that the NGW profile control agent has excellent resistance to high temperature,excellent shear resistance under high temperature and good reservoir adaptability. It is selected as the hot water flooding profile control agent for heavy oil block in the west of Daqing. Through the gel strength test and physical simulation flooding experiment, the selected profile control formula is: SL-AM-APEG copolymer 0.3% (concentration 5000mg/L),cross-linker agent A 1%, cross-linking agent B 0.35%, stabilizer C 0.25%, control agent 0.3%.Through indoor core physical simulation experiments, the best injection parameters are determined as: injection volume 0.7PV, injection concentration 2%, injection rate 0.3mL/min.The residual resistance coefficient of profile control agent is 576.92, blocking rate is 99.83%,breakthrough pressure gradient is 7.2MPa/m, and the blockage rate is 99.78% after 80 ?water driving 10PV, and the oil recovery rate increased by 44.12%, which is suitable for the Du66 reservoir.Using numerical simulation technology to optimize the northern 8 injection wells in the first round of dosage of NGW profile control agent, alternating NGW profile control agent segment plug size and NGW profile control agent concentration, injection speed, profile control time interval parameter optimization values are: 0.07PV, 0.05 PV, 3000mg/L, 16m3/d,and 2 years; two southern injection well test area of the first round of the dosage of NGW profile control agent, dosage of alternating NGW profile control agent, profile control agent NGW profile control agent concentration, injection rate, control time interval parameter optimization values are: 0.08PV, 0.06PV, 3500mg/L, 12m3/d and 1 year. The simulation results are good, which provides the design basis for the field application of NGW profile control agent.The multi factor fuzzy decision making method was applied to scientific selection of wells, and 2 field test target wells were determined. After the implementation, the development effect of heavy oil hot water flooding in Du 66 block was effectively improved,and the experience and technical reserves for the profile control of heavy oil in Daqing oilfield were accumulated.