Hydrodynamics Intensity Method Of Well Patterns And Rate Adjustment In Ultra-high Water Cut Stage

The majority oilfields in our country have entered the stage of special high water cut.At this stage,the major work of enhanced oil recovery is the study of remaining oil distribution and improving the control effects of remaining oil through the well patterns adjustment.This paper focused on the research of the remaining oil's microscopic and macroscopic distribution,remaining oil controlled conditions by the well patterns and the improvements of hydrodynamic controlled at high water cut stage.Based on the microscopic balance and the macroscopic control of remaining oil,the injection and production controlling dynamic method is established for the purpose of improving the water flooding controlled intensity at ultra-high water cut stage through using the basic method of flow mechanics,reservoir engineering,numerical simulation and physical simulation.(1)Based on the microscopic capillary mathematical model,the single capillary,parallel capillaries and flooding capillary mathematical model which is according to the angle of capillaries are established.And these mathematical models are proven correctness by experiments.Results showed that at the sustained water injection stage,when the remaining oil is gathered in fine capillaries,it is possibility generated in crude oil capillary under the only certain condition that not only the injection wells located in the low sites and production wells located in the high sites but also the injection set at slower rate.At the additional water stage,the differential pressure of injection and production is cancelled,the remaining oil in fine capillary will migrate into the crude capillary and the formation of the top remaining oil will be gathering.(2)Based on the microscopic remaining oil at the ultra-high water cut stage,utilizing the method of two-dimensional visualization physical simulation experiments,the water flooding processes in different heterogeneities and residual oil distribution are studied.Through the macroscopic visual experiments,the research of injection water sweeping characteristics at the ultra-high water cut stage and the distribution of remaining oil in different heterogeneities has been further deepened.Nine categories heterogeneous conditions of water channeling characteristics and remaining oil potential area are summarized;(3)Based on remaining oil microscopic balance mechanisms and macro distribution at high water cut stage,for the situations that parts of wells were forced to shut down,an oil re-aggregation mathematical model is established by using flooding mathematical model and the J-function;the policy limits of remaining oil rich region at the high water cut stage are determined;the method make up the insufficient of current simulation deficient relation between the capillary force and the properties..The model can provide a better description of the underground oil re-aggregation at the ultra-high water cut stage.The method utilizes the microscopic mechanisms to improve the level of macroscopic understanding of remaining oil and deepen the study of remaining oil.(4)For the macroscopic residual oil distribution,based on the basic principles of flooding mechanics,a calculation method which consider the physical properties,well patterns,well distance,injection and production well pattern dynamic,of water flooding control intensity is established;this method is studied in different heterogeneous conditions and the applicability of hydrodynamic injection and production control technology at ultra-high water cut stage is studied through changing the injection rates and production rates and adjusting the relations between injection and production wells;results showed that when injection wells located in high permeability sites and production wells located in low permeability sites,the changes of both hydrodynamic methods of well patterns and fluid amounts can improve the water flooding intensity of remaining oil-rich region effectively.Otherwise,only the method of well patterns changes can improve water flooding intensity of remaining oil-rich region effectively in the situation of injection wells located in low permeability sites and production wells located in high permeability sites.(5)Utilizing "remaining oil re-aggregation method","water flooding control intensity " and "well patterns and rate adjustment technology",the dynamic controlling and adjusting technology are established and the application of this technology to actual oilfield,the prediction results showed that this application can make an outstanding adjustment effect.