The Estimation On Polymer Surfactant In Laboratory And Applycation In Test Area

In Xing'wu test area's well spacing of the fourth oil company of Daqing oilfield., polymer surfactant is adopted with four injection, nine recovery and five spots area well pattern. Water injection began from April 20th 2004, with injection pore volume of 0.357PV; Polymer surfactant injection began from October 19th 2005. By the end of 2009, cumulative injection of polymer surfactant was up to 26.12×104m3, which occupy 0.911PV, the dosage of polymer surfactant was 987.7mg/L·PV. In Xing'wu polymer surfactant test area, there has an efficient displacement effect. After Polymer surfactant injection, the moisture content reduced from93%to 70%.Polymer surfactant belongs to graft copolymer, so it has double characteristics -polymer and surfactant, which is different from polyacrylamide. In this paper, we combined with the detection method of viscosity and concentration of polymer surfactant solution, and observed the performance of emulsifier, evaluated the contributed to enhanced oil recovery by the experiment of Core flooding. Combined with production field, this paper solve the problem of viscosity and concentration detection,the severe emulsification of oil-water, reinforces the cognition of Polymer surfactant displacement mechanism.1, The study of viscosity detection methord of polymer surfactantIn the process of detecting the viscosity of polymer surfactant by useing torsion viscosimeter RVDVⅡ, as the molecule of polymer surfactant coupled continuously with each other, the viscosity value of polymer surfactant increased constantly following the time delay. And the viscosity value changed much. It is difficult for the operator to provide the viscosity value of polymer surfactant. The data acquisition software can record the viscosity number of polymer surfactant automatically in situ way.We have concluded as follows by statistical analysis: (1) Analysing the relation between viscosity and time, the data concentrated on the low limit values of viscosity, and the up limit values spread irregularity.(2) After ten minutes, the low limit values of viscosity curve was determined as the viscosity value of polymer surfactant solution.(3) We can also detect the viscosity value at 20 degrees Celsius.The method of detecting the viscosity of polymer surfactant solved the problem how to estimating the viscosity number of polymer surfactant solution, and we obtained satisfactory results.2, The study of emulsification method of polymer surfactantFrom 2008, more and more water-emulsion was picked up from the oil well in Xing'wu polymer surfactant test area. The water-emulsion can be sustained for several months. So we started to study the emulsification of polymer surfactant. In this paper, we standardizes the emulsification method of polymer surfactant to improve the emulsification of polymer surfactant by constanting temperature in advance. But it is difficult to form a stable emulsification system to emulsify electric dehydration crude oil with polymer surfactant. Produced liquid can be demulsificated easily with the effect of emulsion breaker to separate oil and water. The emulsification of polymer surfactant solution is better than ASP. The type of water-emulsion can be identified by a simple method.3, The study of concentration detection method of polymer surfactant"Starch-cadmium iodide" method can not make the different content of polyacrylamide and polymer surfactant. In order to detect the concentrations of polymer surfactant solution, we used ultraviolet absorbing value at wavelength of 234nm, and light-absorbing value is proportional to the concentration.with this character, thus we can detect the concentration of polymer surfactant between 40-800mg/L. The relative error is less than 10%. Salinity and polyacrylamide have little effect to the new method. With combining "Starch-cadmium iodide" method with the new method, we can detect the concentration of polyacrylamide and polymer surfactant.4, The study of enhanced oil recovery after polymer surfactant flooding in laboratoryIn the process of formulating the oilfield development programme,to study the Infuse order and enhanced oil recovery of the water-plugging agent and Flooding wash agent, it is important to improve oil recovery in test area. Experiments show that:Polymer surfactant can improve oil recovery observably, after injecting 0.6PV. with 1000mg/L of polymer surfactant solution, the recovery can increase up to 13%. After injecting typeⅠ, then injecting typeⅢ, with this method, the recovery can increase up to 19.11%. The rate is 5%more than that of injecting typeⅠor typeⅢ. The residual resistance indicates that polymer surfactant can easily stick into the core.5, The apply of polymer surfactant in production fieldAfter injecting polymer surfactant, the injection pressure increased in test area, and injecting volume decreased a little. By the effect of shear force, the viscosity of produced liquid is low, the concentrations of polymer is high. The liquid production and submergence depth decline. Oil production reaches a maximum on January of 2007, and then slowly reduced. At the end of January of 2011, the accumulative product of oil is 11,691 tons from center well, improved 8,006 tons. Stage recovery percent was 18.8%. We have concluded as follows:(1) Comparing with polymer flooding, injection pressure of polymer surfactant flooding increased slowly in the early stage, and increased continued in the later stage.(2) Polymer surfactant solution can increase the volume. The decline of apparent water injection index is higher than that of polymer flooding.(3) The pressure gradient between injection point and injection-production wells was increased.(4) The decline of producing fluid index is close to polymer flooding. Fracturing work can improve fluid situation.(5) Low water-cut lasts a long time. After injecting 0.234PV of polymer surfactant solution, water decreased obviously. After injecting typeⅢpolymer surfactant solution, water decreased again.(6) After injecting polymer surfactant, emulsification can be observed in the produced liquid of center oil well.(7) Responding in Production well related to the development and surplus oil distribution of the oil reservoir(8) Fracturing work can improve injection-production status obviously.(9) Tons of oil increasing gathering and stage to improve oil recovery is higher than that of polymer flooding.