Research On Completion Water Control Of Double - Horizontal Well In Bottom Water Reservoir

Bottom water coning is the biggest problem in reservoir with bottom water, due to coning, water breakthrough in advance, production fall sharply, water cut increase fast and eventually water treatment cost and development cost rising. So the key technology of bottom water reservoir development is inhibiting bottom water coning, extending water-free production period and controlling bottom water to displace equably, which can improve development. In order to reduce water cut growth, regain and raise oil production, BWS (Bilateral Water Sink) technology has been carried out to control bottom water coning and to solve bottom water coning fundamentally, simultaneously BWS provided research approach and method for the quick and efficient development of reservoir with strong bottom reservoir.Basing on a great deal of researched literatures, combining field test of the reservoir, the article employs semi-analytical simulation model to research on the influencing rules of BWS factors and parameter optimization. According to methods of mirror and the superposition of pressure drop, the pressure loss model of reservoir was established by using source function. Based on the seepage characteristics of different completion in near-wellbore area, the near-wellbore flow model was gained. The pressure loss model of wellbore was founded in accordance with the conventional pipe flow in blank section and the variable mass flow in production section. Then by coupling these three models, the productivity forecast model was derived. Considering the elements such as anisotropy, filtering interference, conduit flow drawdown as well as damage zone caused by drilling and/or completion, a full set of loop iteration solving schemes for the stable coupling model have been established by means of discretized semi-analytic method. Then, with the help of computer programs, which are compiled on the base of the scheme mentioned above, rate distribution profiles and flowing pressure distribution profiles have been worked out. The influence of the reservoir geology characteristic parameters and process parameters to rate distribution profiles has been analyzed.Then, by analyzing the mechanism of the water cresting in2D and3D models, a3D mode of BWS has been established.The distribution of bottom water breakthrough time and lifting height along the horizontal wellbore location has been gained. The influence of oil viscosity, anisotropy, water avoidance height, wells location, well radius and drawdown pressure to breakthough location and breakthough time has been analyzed. As the results show, oil wellbore is more close to the top of the reservoir, the longer the bottom water breakthrough time, As the well moving up, the breakthough time increased faster; With the increase of kh/kv ratio, breakthrough time increased; The higher the viscosity of crude oil, or the greater the thickness of bottom water, effect is more poor. Finally, applying the coupling productivity model and three dimensional bottom water cresting model of BWS completion, setting cumulative free water production rate as objective function, calculating the cumulative free water production rate with standalone screen completion and BWS completion, the results show that the cumulative free water production rate is much larger when mining well length is short; when mining well is middle and lower, the effect of BWS is better. Optimize the length, position and drawdown pressure. Enumerate four different programs of selective completion, finally finding out the best one.The outcomes of this research could be the theoretical basis of optimizing the completion method and parameters of BWS. And it could help to instruct the oil companies to design the BWS completion.