Heavy Oil Injection Steam Ball Plug Lift System Model

Although sucker-rod pumping is the most used artificial lifting technique on steam-stimulating well, many difficult problems are still remains: the friction between sucker rods and casing pipes is severe; the emergency of collapse and dropout happened frequently and the pump checking period is short. A new kind of artificial lifting technique which named as steam-pig lift technology is put forward. It has the structure of U-shaped double completion string (one for injection, the other for production), use steam instead of nature gas as lifting medium and launch the lifting boll into lifting medium to increase lifting efficiency. The advantages of steam-pig lift technology are obvious: firstly, the injected steam can reduce viscosity of thick oil by heat up wellbore and reservoir, secondly, steam mixes up with oil formation liquid to reduce the density of lifting liquid; thirdly, By launching the ball into the injected steam, it can form the stead slug flow and prevent liquid to fall back because of the solid interface between gas and liquid phases; fourthly, the lifting capability of pig lift can be adjusted easily to accommodate the production capability of steam-stimulating well; fifthly, steam-pig lift technology can utilize the steam injection pipeline and boiler of cyclic steam stimulation and economize money.Due to use steam as lifting medium, how to keep up the dryness of steam and to prevent superabundant condensation water to form is the most important technique. This paper does some research on injecting, lifting process and heat transfer characteristic of steam-pig lift technology. Apply Mukherjee-Brill relationship and Ramey-Willhit's wellbore heat transfer theory to establish steam injecting model which can describe the speciality of tow-phase flow and heat transfer. By using the model, the most important parameters such as steam dryness, steam temperature, steam pressure, casing tempture, heat loss can be calculated correctly. On the base of error statistics, suitable model can be seek to simulate multiphase flow processes which conclude the process of using lifting ball or not. Node system analysis is applied to optimize steam-pig lift process. By protracting characteristic curve of steam lifting, we can optimize the key parameter such as steam injecting velocity and injecting steam dryness.Taking thick oil well of Kelamayi oil field as example to demonstrate the feasibility of steam-pig lift technology and do some research on the factors such steam injecting velocity, steam injecting pressure, steam injecting dryness, tube diameter, injecting depth and so on, which effect steam dryness in U-shaped double string and heat loss ratio. Comparing the...