Experimental Research on Placement Law of Injected Agent in General Water Shutoff for Horizontal Wells

Abstract

In order to research the placement law of injected agent in general water shutoff for horizontal wells, injection and water plugging experiments were carried out based on horizontal well models. Normal model was modified to research placement of gel quantitatively. Plane heterogeneity and well trajectory changes were also considered in the models. Experiments results indicated that injected agent was not uniformly placed along the horizontal direction in general injection. The agent was more likely to enter the zone near heel end because of pressure drop along horizontal well. High permeable area and lower well part were both favorable factors for blocking agent’s entrance. The final placement was determined by the game between the factors and pressure drop. When the two factors existed at heel end, the non-uniform placement would be even intensified, and the differences among each part would enlarge. Conversely, when the two factors existed at toe end, it was beneficial to make the placement of injected agent more uniform. The performances of general water shutoff were influenced by the placement law of injected agent. The breakthrough water will be better plugged if more of injected agent went to objective position, which induced a better oil production after the treatment. Therefore, researching and making use of the placement law of injected agent is beneficial to improve the performance of general water shutoff in application.
Key words: Water plugging experiment; Water shutoff; Horizontal wells