Study Of The Decision Method And Forming Condition For Wells And Layers With Low Efficiency Circle

At present most oilfields in the world have been developed by water flooding, because water flooding can make the oilfield maintain high-volume withdrawal for a long time and it can also improve the final recovery efficiency greatly. In our country, some oilfields have been in the later stage of water flooding development, and many oil wells has been with high water cut or super high water cut. The reservoir structure has been changed for long period of washing by injected water. The big pore channel has been come into being between oil and water well, which bring on the low efficiency circle of injected water and decrease the output of oil well. The wells and layers with low efficiency circle have to been controlled by measures such as profile control or water plugging and so on, so as to improve the effect of water flooding, and the key is to recognize them.In this thesis, a lot of data about big pore channel in home and abroad have been surveyed, and the influential factors of big pore channel and the characters of water and oil wells with big pore channel have been analyzed and summarized. Three types of low efficiency layers have been summarized in this thesis, and ideal models have been established for each type to do the numerical simulation. Then the formative condition for low efficiency circle layers has been determined. Combined with the condition of real data of Beisandongdong region in Daqing Oilfield, parameters have been confirmed for the determination of wells with low efficiency circle. Because on the nonlinearity relationship of each parameter, fuzzy integrated evaluation method has been used in this thesis to establish the mathematical model. Aimed at the judgement result of oil and water wells with low efficiency circle, decision method for layers with low efficiency circle has been studied. This method based on the contrast between static data and sediment microfacies, and the relativity between oil wells and water wells, and combined with fuzzy integrated evaluation.Based on the method above and combined with dynamic and static databases offered by Sabei development area of Daqing Oilfield, a software has been programmed for analyze and judgement of wells and layers with low efficiency circle. Layers with low efficiency circle of Beisandongdong region have been selected by the calculation with this software using real data of this region. Through the contrast of the truth of the region it indicated that is method is practicable and work efficiency and veracity can be improved greatly.