Study And Application On Profile Modification In Mid-low Permeability Reservoir

Jiangsu Oilfield is a typical small complex fault block oilfield. Mid-low permeability oil reservoirs account for a large proportion in developed oilfields. Jiangsu Oilfield now is in high water cut period, the reservoir heterogeneity in vertical and horizontal are becoming more and more serious. Separate injection procedure can not treat the problems of water fluctuation between layers and water channel in injector because of numerous small and thin layers. To solve these problems the profile modification indoor research and field tests.Profile modification potentiality evaluation model of Jiangsu mid-low permeability reservoir is established and comprehensive evaluation and quantitative comparison of the potentiality of each developed unit is realized. Reservoir adaptability of the 3 typical block agent systems which are commonly used in oilfield, such as Na2SiO3-CaCl2, HPAM gel and gel particle is evaluated.A new crosslinker JL-B2 and gel JSGY-1 which are used in the reservoirs below 70℃ is developed. Aiming to decrease the filtration on fracture matrix in reservoir, a new secondary crosslinked plugging agent is gained on the base of secondary crosslinked plugging agent in hand by reforming the first crosslinker, which is used in the reservoirs of 65℃~90℃. The effects of injection pattern and slug size on injection pressure and pollution level of non-target layers are investigated by sand pack model in complex profile control of medium-low permeable reservoirs. The blocking remover formula and the concentration are optimized. The formula is tested in two well groups and success rate of profile control is 100%, while for oil well the efficiency is 96%. It effectively improves the intake profile of water injection wells and eases conflicts of inter-layers and intra-layers, which is worth expending andapplication.This report on the base of scientific decision of profile control, which aims to adapt reservoirs, plugging agents and injection each other, supplies theory and technology base for Jiangsu Oilfield profile modification treatment. It is helpful for the water injection in high water cut oil filed, also helpful for the chemical flooding in Jiangsu Oilfield.