Study Of Profile Control And Water-shutoff For Horizontal Well

For complex reservoirs (low permeability, ultra-low permeability, heavy oil reservoirs, etc.). generally using horizontal well technology can be cost-effective development. However, with the exploitation of reservoirs, the improper working system or the injected water entering into the horizontal section through crack will cause the problem of horizontal wells producing water, then the measures of profile control and water shutoff should be taken. Owing to the complex structure of horizontal wells and complicated features of reservoir geology, profile control and water shutoff in horizontal well is more complicated than that in vertical well. The complexity of horizontal well profile control and water shutoff lies in that horizontal wells EOR requires blocking agents more stringent,but there is no specialized agents for horizontal wells water shutoff, therefore, suitable blocking agents for horizontal well are urgent needed. Horizontal wells EOR process requires controlling plugging agent into the purpose blocking layers effectively. Based on the reason of water problem and the characters of reservoirs, this paper focuses on the water problem in horizontal well.(1) By researching different blocking agents used in horizontal well water shutoff and comparing their characters and performances, phenolic polyacrylamide and pre-crosslink particles blocking agents are determined to be researched.(2) For phenolic weak gel system, through experiments, optimal formulation research is conducted. Weathering performance, the rheological properties and core plugging performance also are studied under the best formula.(3) By orthogonal experiment, the plugging agent absorbing performance of the pre-crosslink particle gel are studied. And Temperature resistant and salt resistant performance, selective plugging properties are studied.(4) Including injection method, combinations of the slug is confirmed. Optimized construction slug is multi-way slug shutoff. And use the results of previous studies to determine the amount of blocking agent injection, injection pressure and injection displacement and other construction parameters. According to the research results, to select the injection equipment and processes. Study for construction site behind the two wells, the results show that after EOR, water absorption index decreased, the pressure drop curve is slow, oil production increase significantly.The weak phenol aldehyde gel and pre-crosslink particles gel studied in this paper have a good selection property, high temperature resistance and chemical stability, high safety for small formation damage and field operational characteristics, can meet the requirements of horizontal wells EOR technology. Deep EOR process is simple, meeting the technical requirements of horizontal wells EOR.