Research on the Technology of Paraffin-Controlling and Viscosity-Reducing for Crude Oil Based on the Utransonic Transducer Array
|School||Harbin Institute of Technology|
|Course||Mechanical Manufacturing and Automation|
|Keywords||crude oil piezoelectric transducer transound-based on paraffin- controlling and viscosity-reducing transducers array sound field analysis paraffin deposition|
Most of the crude oil produced in China was viscous crude which contains lots of paraffin with high-viscosity and high-congealing point, during the process of the crude oil being transported through the pipelines to the ground, the paraffin dissolved in the crude oil will deposit on the inner surfaces of the pipes, and thus block the pipes, reduce the effective diameter, which is termed as paraffin deposition. This is an essential issue needed to be taken into account during the production and transportation of the crude oil, especially in the cold areas or through the sea exploitation pipelines. Lots of methods used to paraffin-controlling and viscosity-reducing of the crude oil have shortcomings such as expensive or quite often in operation or the well being subject to stopping production. These approaches above have a common on easy recovery of viscosity and can not eliminate the paraffin deposition fundamentally. However, an ultrasonic treatment can not only change the paraffin crystal morphology, but also stop the crystal growth, disperse the crystal particles, and decrease the paraffin deposition, therefore the viscosity of crude oil is reduced effectively, as well as it can reduce the flow resistance greatly in the pipelines and play a role in saving energy and reducing consumption under the condition of non-polluted oil layers.Based on the theoretical analysis of characteristics of paraffin deposition mechanism, the mechanism of ultrasound-based on paraffin-controlling and viscosity- reducing is investigated respectively from the machanical effect, cavitation, emulsify- cation and thermal effect. The effect of acoustic parameters on vibration of single bubble is simulated, which provided foundation for the design parameters selected for transducer.Based on one-dimensional vertical vibration? wave equation of variable cross- section, a half-wavelength transducer oscillator and half-wavelength horn are designed respectively, using Boundary-Condition Method and Transfer Matrix Method, which develops a whole-wavelength power collected transducer by connecting the two parts with a bolt. And the design parameters are validated by simulations and experiments, which provides the core components for ultrasound-based on paraffin-controlling and viscosity -reducing device.The directivity and sound intensity of sound field has effect on the ultrasound- based on paraffin-controlling and viscosity-reducing, and it’s well resolved by transducers array. So based on the Huygens integration theorem, in this paper, it’s derived that the Directivity and acoustic pressure distribution of sound field function of the circular transducer radiating, as well as its Combination of plane linear array. It’s calculated numerically, then the effective range of the sound field is determined, design the experimental device for ultrasound-based on paraffin-controlling and viscosity- reducing, which provide the conditions to the next experiments. In order to detail the effects of the ultrasound treatment-based parameters such as treatment time, the current of the transducer, moisture content, paraffin content, flow rate and oil temperature on viscosity-reduction and paraffin-controlling of crude oil, a series of experiments have been carried out using the device developed and evaluated accordingly. The paraffin crystals morphology under the different conditions of parameters are observed, and thus demonstrates that the paraffin crystals morphology changes from layered or sheet to spherical particles, and dispersed uniformly in the light crude oil upon ultrasonic treatment. Analysis of paraffin liquid chromatography shows that the carbon chain of paraffin can be interrupted by ultrasonic.In the paper, the experimental results indicate that, ultrasonic wave can interrupt the molecular chain of paraffin, change the paraffin crystal morphology, reduce the viscosity of crude oil and condensate, increase in fluidity in the low-temperature. It’s also proved that an ultrasound-based treatment proposed is not only of the effectiveness, but also of non-recovery. At the same time, the optical parameters for ultrasound-based on crude oil are determined, which provide a certain guide to the ultrasound-based on paraffin- controlling and viscosity-reducing products in oil field.