Studying On Integrative Temporary Water Plugging And Acidize Technology

Most blocks of the ChangQing oil field are low-pressure,low-permeable and low-bearing sand rock reservoirs with the characters of aeolotropic and multiple zone. The majorities of oil wells are developed by fracturing and water injection.Because of the high permeability zone and fracture orientation in the oil reservoirs, injected water develops vertical monolayer breakthrough and horizontal fingering. Therefore the effect of water injection in the mid-permeable formation and low-permeable formation cannot meet demand, thus oil wells are water flooded prematurely, and the effect of waterflood development is not good.At present,one of the main reasons of the low-deliverability in many wells is the exorbitant water content ratio and the damage of formations. There are two primary chemical techniques to control profile,one is chemical water plugging, the other is acidification of the water well which adopts acid treatment to low-permeable formation, thus improves the liquid producing capacity of low-permeable formation and ameliorates water injection profile. However, there are some problems towards adopting conventional acid treatment in some water wlls that have comparatively severe aeolotropism among high-water-bearing stratum: the injected acidizing fluid will follow the principle of least resistance, most of which will enter into high-permeable aquifer but not the low-permeable oil layer, thus after acid treatment of water wells, the water production of corresponding oil wells rises, the crude output seldom increases even deceases.This article carries out a integrative temporary water plugging and acidize technology. this technology uses one bridging solid temporary blocking agent that be defined by the rule that solubility of water and acidizing fluid in different temperature in laboratory experiments, also with the theory of matching mechanism between granule diameter and high permeable layer and re-less permeable layer, this technology can make out some temporary blocking area that their permeability is low in re-less permeable end face. The temporary plugging agent can decrease layer’s porosity when the high permeable layer have laid down. Because of heavy anisotropies in high permeable layer, bridging solid grows jam in micro bore of high permeable layer, so the acid proof blocking agent not only can be injected selectively, but also increases the distance of blocking. Take the pang33-32well for example, in the eye of water block removing,the effectiveness of the recovery of acidize permeability is very obvious. For the integrative temporary water plugging and acidize technology, acidizing the temporary blocking is available.