Well Groups Classification And Injection Scheme Optimization Research Of The Western NanEr District’s Sub-layer

As the main layer polymer flooding block polymer injection begin to end gradually,for some time now the key polymer flooding is the sub-layer. Because the sub-layer plane and vertical the sand body development is small scale, sedimentary facies change quickly, although the polymer flooding objective layer has extended to the effective thickness is equal or greater than 0.5m,the permeability is equal or greater than 0.1μm2,but in the actual development process, in order to improve injection production relationship, the thin and poor layer and the outer table layer in the development layer also shot to produce at the same time, from the sub-layer has the industrialized production of the actual development effect, because of the interlayer interference, polymer type, the adaptability of injection concentration among the different reservoir, the thin and poor layer that effective thickness below 1.0m producing degree is poor, the ratio of effective thickness producing degree is around 50%, the ratio of the outer table layer thickness producing degree is 30-40%. For ensure the sub-layer effective producing of the western NanEr District, the different well group need to fine polymer injection, namely to different well groups have the corresponding injection parameters.This paper through the method of the single factor analysis and grey correlation analysis to analysis the nine static and dynamic factors and determine the main factors affecting the effects of the western NanEr District sub-layer’s development effect.And makes a classification of the western NanEr District sub-layer’s well groups by using the fuzzy comprehensive evaluation method. Using the PETREL software to model the block’s geological model, using the orthogonal design method to design the experiment scheme,using ECLIPSE software to simulate the each kind of well group’s scheme, through differential analysis to give the each kind of well group the best injection parameter.This established the western NanEr District sub-layer’s development foundation and provide the effective technical support for other blocks of the sub-layer’s development.Research shows that: the six main factors affecting the effects of the western NanEr District sub-layer’s development effect are the degree of reserve recovery before polymer flooding, permeability contrast, permeability, effective thickness, control degree, the water saturation before polymer flooding. Using the fuzzy comprehensive evaluation method divide the well groups in the block into 4 categories. Through the geological modeling win the block structure model, sedimentary facies model, attribute model and calculate the block’s reserves, fitting error between the calculation and actual geological reserves is smaller, use the method of orthogonal to design the scheme of the injection well groups. Through differential analysis the results simulated via ECLIPSE software to know: the one well group’s best injection scheme combination polymer molecular weight is 2000×104, the polymer concentration is 1000mg/L, injection rate 0.25PV/a,injected slug is 0.57PV; The two well group’s best injection scheme combination polymer molecular weight is 1600×104,the polymer concentration is 1200mg/L, injection rate 0.2PV/a, injected slug is 0.57PV; The three well group’s best injection scheme combination polymer molecular weight is 800×104,the polymer concentration is 1000mg/L, injection rate 0.1PV/a, injected slug is 0.64PV;the four well group’s best injection scheme combination polymer molecular weight is 800×104,the polymer concentration is 1000mg/L,injection rate 0.25PV/a,injected slug is 0.57 PV.