The Research Of Water Flooded Layer Interpretation Method In Laojunmao Oilfield

Laojunmiao oilfield is the earliest developed oilfield in our country and has entered a period of high water cut with the deepening and development, of which the basic research is weak, The old logging series is different from the new one, the measurement of early logging instrument is simple and electric logging is mainly for ordinary resistivity logging. The ordinary resistivity logging method, including gradient and potential resistivity logging, doesn’t match with the lateral resistivity logging series in the process of old well review and multiwell evaluation. Laojunmiao oilfield, at present, mainly depends on the qualitative identification for evaluating the water flooded layer and the quantitative evaluation is complementary. The coincidence rate of quantitative evaluation of appraisal well is not satisfactory, which is harmful for the second time or the third time development of old oilfield. Therefore, it is very necessary to carry out the comprehensive interpretation method research of water flooded layer.This paper is on the basis of the actual geological and development characteristics of Laojunmiao Oilfield, combined with geological, logging, well logging, testing, core experiment data analysis.At first, there is a research on the relationship between the lithology, physical property, electric property, oil content and the changes of the related parameters;Secondly, by contrasting the ordinary resistivity and lateral resistivity logging data, a model about transformation of the ordinary resistivity and lateral resistivity logging data is established based on the BP neural network, and 23 wells are processed and the result is satisfactory;Thirdly, the injected water is complex, in the early days, it is the fresh water, then sewage recycle in late stage. In view of the characteristic in the study area and starting from conductive mechanism of the formation, two sets of dynamic evaluation method have been established to compute mixture formation water resistivity of water flooded layer based on pure sandstone conductive model and argillaceous sandstone conductive model, which laid a foundation for quantitative comprehensive interpretation of water flooded layer and 121 wells are processed, of which the calculation of mixture formation water resistivity is almost the same with the water analysis of formation water resistivity;Fourthly, there is no property curve measurement of old well, so in order to establish the porosity and permeability model,0.6 meters resistivity and amplitude difference of spontaneous potential are choosed. And then, according to 2.5 meters resistivity, amplitude difference of spontaneous potential and porosity, the oil saturation model is established, and for the new wells, the corresponding models are established with the conventional logging data, and precison has reached the requirements after dealing with 301 wells;Then, an intersection chart is established according to amplitude value of the spontaneous potential and acoustic time after the water flooded characteristic and the logging response characteristic is studied. The original oil saturation is accurately calculated according to the inversion method of original oil saturation and can be easy for the qualitative identification of water flooded layer by contrasting with the residual oil saturaton;At last, the physical property plane distribution is studed and so is the remaining oil saturation and the enrichment region is determined. The relative permeability model is established, based on the phase permeability experiment data. Then, the water production rate and the oil displacement efficiency formula is determined. The quantitative classification standards of water flooded layer is established by using water production rate and oil displacement efficiency. Coincidence rate of water flooded layer interpretation has improved with dealing with 98 wells, which shows that the method is applicated and reliable.