Researching For The Test Of Continented Sandstone Reservoir

In the process of exploration and development of oilfield, acidification and fracture are important means of the oil reservoir reconstruct. The effect of acidification is involved in the lithology and mineral feature of the reservoir.This paper, took low-permeability reservoirs of Changyuan region in Daqing oilfield as studied object, selected the typical core and made the analysis of clay mineral composition, rock appearance and structure, sensitivity feature,The analysis of petrography shows that more shale and calcium caulking compound is one of the feature of low-permeability reservoirs of Daqing oilfield. Feldspar and detritus, constituting as much as 60-70%, are more active than quartz in the diagenesis and acid treatment. These components dissolution in the acid treatment may result in serious reservoir pollution. It is main reason why the mud acid treatment effect of terrestrial facies reservoir is poor.Clay mineral contain rich illite and chlorite but lean kaolinite and illite/smectite mixed layer. The latent factors effecting the operation are fine particle migration and acid sensitivity.According to laboratory acidification experiment, M2 type acid is effective to the low-permeability reservoirs of Daqing's peripheral oilfield. It not only increases the permeability of reservoir but also minishes the influence of clay mineral migration, thus sequent treatment fluid can be returned.Examined under the scanning electron microscope, it is well visible that in acid treatment clay mineral beside the wide pore and throat of the reservoir rock is firstly dissolved so that the permeability of reservoir should be improved. The clay mineral in the binding pore will not be dissolved so irreducible water will not be released.