Effect Of Bubble Characteristics And Improve The Flow Of Tahe Heavy Oil

Petroleum is the blood of the earth, and the power source for the sustainable development of world industry and economy. With the depletion of conventional crude oil, the economic utilization of such abundant heavy oil resources has become a common issue faced by the world petroleum industry and national governments. Heavy oil is characterized by high viscosity and easy solidification, its severe adhesion in the wall of wellbore, pipeline and production equipment has brought great difficulties to its recovery. Inspired by micro-bubble drag reduction theory and water lubricated heavy oil transportation technology, a new idea of aqueous foam lubricated transportation of Tahe heavy oil is proposed in this paper, the basic research work in this paper has certain practical significance to explore a new heavy oil flow drag reduction method.On the basis of investigation of the research advance on foam system and and water lubricated heavy oil transportation technology home and abroad, the basic properties and pipe flow characteristics of two Tahe heavy oils were measured. An aqueous foam system AFS-2with high stability was screened out by using Wairing Blender method, and the influences of temperature; salt and oil on the performance of AFS-2were evaluated. The micro structure of AFS-2foam was measured by using XP-300C image analysis system. Foam rheological properties were measured by Anton Paar Rheolab QC rheometer, and a correction method for wall slip elimilation was proposed. Based on the existing flow loop apparatus, accessories including foam generator, a tank for foam injection, and foam layer generating device were designed. The foam lubricating effect on the two Tahe heavy oils flow in horizontal and upward pipes were studied experimentally, and two basic models for pressure drop calculation of foam lubricated heavy oil fow in horizontal and vertical upward pipe were presented based on the analysis of experimental phenomena.The results show that the two Tahe heavy oils THCO1and THCO2are common heavy oil, which exhibit Newtonian fluid behavior within the temperature range of20℃to60℃. The composition of AFS-2is100mL H2O+1g/L ABS+1g/L3#+3g/L PAM+3g/L SF-1+3g/L dodecanol; the foaming output and the foam half-time of100mL AFS-2liquid, which were measured using Waring Blender method at the temperature of15℃and the pressure of101325Pa, are380mL and6050minitues respectively; the foam belongs to Fine Celled Foam category with irregular polyhedral shape bubbles, which diameter distribution is between10～100μm. Temperature, salt and oil can influence the foam performance intensively, with the temperature, amount of oil and salt increasing, the foam stability is deteriorated rapidly; light oil is more destructive to the foam than heavy oil, and CaCl2is more destructive than NaCl. More serious wall slip presented with the greater shear stress, the smaller viscometer bob and annular gap, and the rheology of AFS-2foam without wall slip is accordance with the Power-law rheological model. The drag recudtion effect of dry foam with74percent of gas content on THCO1oil is poor, because the density of the dry foam is much smaller than that of THCOl oil, and this leads to a stratified flow of heavy oil and the foam in horizontal pipe. However, the situation is different to wet foam with30percent of gas content. For the flow rate of6to12L/min of THCO1heavy oil, the drag reduction of the wet foam is not efficient when the foam flow rate is smaller than0.5L/min (flow rate ratio of foam and oil is less than10%), because it can not form an integrated lubrication layer in the pipe with so less foam. When the wet foam flow rate is increased to1to3L/min, its drag reduction efficiency reaches75%, and the drag reduction effect is slightly better with less foam. In the vertical upward flow, for the THCO2heavy oil flow rate of5to11L/min, the drag reduction effect of the dry foam is poor when the foam flow rate is less than0.5L/min, and the drag reduction efficiency is up to70%when the foam flow rate reaches to1to5L/min; and the greater the foam flow rate, the smaller the heavy oil flow rate, the smaller the pressure drop measurements. The fundamental pressure drop model for foam lubrication heavy oil flow in horizontal pipe has a deviation of-28%to18%with respect to the measurements; and the model for vertical upward pipe has a deviation of-31.4%to11%.