Experimental Investigation of Water Injection Effects on Formation Damage and Rock Structure

In this research, effective parameters of injection process such as flow rate and rock lithology, for one of Iranian giant fields, were studied under different situations, using laboratory physical model. The physical model consisted of this mentioned reservoir rock, formation fluid and injection fluid samples. Precise investigations were performed to reveal the effects of suspended particles and their movement through porous media by comparison of the results for filtrated and unfiltrated injection water. Increasing of flow rate in unconsolidated sandstones resulted in disordering of porous medium structure and creation of channels was easily observed in case of micro-fractures existence. Experimental investigation was disclosed that induced fracture in rock sample could result in injection pressure decline during first periods of injection. Unfavorably, this fracture may play the role of a channel which transfers the suspended particles or results in taking apart of particles from rock matrix. In a long period, these phenomena result in pore plugging. Plugging usually occurs in long distance form production well and in case of coming close to production well, pressure decline and consequently production reduction would be detected. Notwithstanding, for sandstone samples, significant injection pressure was not detected following by flow rate buildup, experimental observations and results showed that pore plugging and consequently permeability reduction could be distinguished as a result of particle movement through porous medium in a long distance and during extended time period.