Balanced Injection and Production Technique for Horizontal Wells Based on Inter-Well Connectivity

Abstract

Because of the long horizontal length and the reservoir heterogeneity, the water production and injection are different along different locations of a horizontal well. So the conventional water injection string are not suitable for horizontal wells. Besides, the conventional models for inferring interwell connectivity between directional wells are not suitable for horizontal wells. In this paper, a new model for inferring interwell connectivity between horizontal wells is built and a new water injection string for horizontal injector is presented which can meet the demand of water injection of different locations for a horizontal well. Based on the conventional water injection string, a new packer was installed at water injection string with the location's deviation less than 60 degrees. A Water distributor working cylinder was installed to respectively distribute water to root and toe of a horizontal well. Inorder to characterize different sections of a horizontal well, a horizontal well can be considered as several directional wells with different physical properties such as permeability and porosity and so on. Based on this, the reservoir is characterized as a coarse model consisting of a number of interwell units which is controlled by any two directional wells. Injection and production data were used to infer interwell connectivity and geological characteristics. The results obtained from the new proposed model are in consistent with the oxygen activation of injectors. Interwell connectivity coefficient of each injector were calculated and the preponderance flow paths were found. Based on this, profile control were conducted. After profile control, the water injection efficiency of horizontal injectors obtained by this model improved and water cut of produces was reduced by 9% ~ 10%. This technique has been used in nearly 100 wells of Bohai oilfields. With the inter-well connectivity method and the balanced injection string for horizontal wells, the development effect of reservoir with horizontal wells improved significantly.