Research Of A Kind Of Glycolipid Biosurfactant And Its Application In Heavy Oil Viscosity Reduction

With the rapid development of the economy, the recovering.of conventionalcrude oil can not satisfy the state quantity demand of the energy increases more thanbefore. In order to balance the supply and demand of energy source, people begin topay more attention to the exploiting of the unconventional crude oil. Due to thecharacteristics of high viscosity, high density, high condensation point and thedifficulty of flow, how to reduce the viscosity and improve the liquidity of heavy oil isconsidered to be an important problem. At present, the method of heavy oilexploitation has been researched for a long time. But there still are some problemssuch as high operating costs, destroy the oil reservoir geology environment, secondarypollution and so on. Microbial viscosity reduction technology is attracting widespreadintrests based on its high stability, low cost, high tolerance to extreme environment,high economic efficiency without secondary pollution.This paper choose the heavy oil of shengli Gudao oilfield as the research object,aiming at using a combination of chemical and biological methods to reduce theviscosity of heavy oil, to obtain more efficient environment friendly heavy oilcompound viscosity agent. This compound method will not only avoid the secondarypollution of formation environment caused by chemical viscosity reducer but alsogive full play to the advantages of biological method, to improve the effect of heavyoil viscosity reduction. Fermenting the biosurfactant-producing bacteria, strain Bbai-1and then identificating the metabolites by physical simulation experiment indoor.Using biosurfactant or the fermentation broth combing with chemical viscosityreducer SB-2interacted with the heavy crude oil, the visbreaking compound systemcould emulsificate the crude oil. The conclusions were presented in the following:（1） The fermentation conditions of Brevibacillus parabrevis Bbai-1were optimized to be temperature of25℃, the salinity of8g·L^-1and the pH of7.5. Underthe optinium conditions, after168h bacteria culture process using fermentation tank,the pH of the fermentation reduced to be5.6from the original pH of7.5after thewhole process. At the same time, the maximum total viable count could reach up to3.1×109cell·mL^-1. At the time of96h, the surface tension reduced to be29.61mN·m^-1.Therefore, the proper time to extract biosurfactant was in the mid-to-late（96¹44h） ofthe stable growth period and the yield could reach up to2.12g·L^-1.（2） The CMC of this biosurfactant was120mg·L^-1. The surface tension of watercould be reduced into27.62mN·m^-1under the effect of this biosurfactan.Thebiosurfactant had better stability and surface activity while the temperature, pH andthe salinity were in the limits of15⁸0℃,3.0¹3.0and0¹0%respectively. Inaddition, the emulsification of the biosurfactant was very well. Its emulsifying abilitystill maintained at44%after7days continue testing. Through a series of analysis,the glycolipid biosurfactant was classified as rhamnolipid and the structure wasproposed as follows:（3） The optimum visbreaking compound system containing chemical viscosityreducer SB-2and the fermentation broth of strain Bbai^-1 were detected to be: thedosage of SB-2was2.0g per1kg crude oil, the fermentation broth usage of Bbai^-1was50%under the optimum oil-water ration5/5. Then the viscosity reduction ratewas tested to be96.43%.（4） After heavy oil samples interacted with the chemical viscosity reductionsystem and the visbreaking compound system, the gas chromatographic analysis wasdone. The results indicated that under the premise of maintaining heavy oil quality,compared with chemical viscosity reduction system the chemical-biological complexsystem has more economic and environmental benefits.