Study Of Water-flooding Effect At Naniwan Ultra-low Permeability Reservior

Nanniwan oilfield Ch4+5reservoir and Ch6reservoir is typical of low porosity,ultra-low permeability and low saturation reservoir. Its reservoir physical property is poor,seeping resistance is bigger and natural productivity is very low. Since September2006the implementation of water-flooding trial, the development effect is improved, but thereare still some problems. So it is very significant to study Nanniwan ultra-low permeabilityreservoir on characteristics and effects of water-flooding development.First, analysis on the reservoir characteristics in this paper shows that its poretypes mainly include intergranular pore and dissolved pore which mainly contain feldspardissolved pore, lithic dissolved pore, laumonite dissolved pore. Second, through analyzingproduction dynamic data, it can be concluded on the decline type of the block andproduction characteristics, and researched on the choice of injection-production pressureand the suitability of well pattern system. Third, it is analysed on the change of water cutand the effect of water-flooding, is evaluated on the utilization of the water injection and iscalculated on producing degree of water-flooding reserves and the coefficient of water cutrising. At last, by using several methods it can be determined that the reasonable density ofproduction well is28.39/km2, the reasonable spacing of injection-production is165m, thereasonable ratio of injection-production is1.53. The comprehensive evaluation on currentwater flood development effect can provide reliable basis for compiling reasonable andeffective development plan in the future.The research shows that the effect of water flooding development in Song700wellblock got better gradually, it mainly reflect on the slowing down of production decline andthe slowing down of natural decline rate. But water injection volume is not enough and thewater injection pressure is not high, there are still much potential. In the study block thereare some problems that the current perforating thickness of both production wells andinjection wells is thin, the perforating formation are incomplete, parts of the well groupare not corresponding. In order to enhance production some effective measure should betook to increase the perforating thickness of production wells and injection wells toincrease the vertical sweeping efficiency. This paper puts forward the reasonable well pattern adjustment plan of Song700well block to guide oilfield development.