Analysis of Key Sweetspot Identification Methods and Their Significance for Hydrocarbon Well Placement

Abstract

Sweetspot identification methods are of significant value in optimizing well placement in reservoir simulation studies. These methods vary in their approaches due to the wide-ranging reservoir characteristics and different study objectives. This work analyzes a number of sweetspot identification methods and discusses their advantages and limitations. In addition, we establish a workflow that utilizes a combination of a number of reliable methods. A simulation model of a synthetic heterogeneous reservoir with six million grid-cells is used in this work to evaluate six sweetspot identification methods for the purpose of well placement. The evaluated methods use grid-cell productivity, fluxes and sweep ratio as well as a combination of a number of rock and fluid properties to generate sweetspot 3D maps. Using sweetspot maps from the analyzed methods and the proposed workflow, different well placement scenarios are developed and compared. Results are compared using total hydrocarbon production and voidage replacement ratio. We observe that wells placed using grid-cell productivity maps achieve significant improvement in the total hydrocarbon production over a period of ten years when compared to the other analyzed methods. This method identifies the high productive grid-cells which results in the best performance of wells among the analyzed methods. However, this method provided less emphasis on the grid-cells proximity and connectivity in the sweetspot map. In heterogeneous reservoirs, this can result in tortuous trajectory paths, which are impractical to drill. The flux-based method yielded less hydrocarbon production, but higher voidage replacement ratio. The proposed workflow demonstrated considerable improvements in the total oil production and a balance in voidage replacement ratio. The new workflow retained the advantages of different methods maintaining a balance between their strengths and marking distinct methodology that can be used for well placement optimization. This work highlights potential opportunities to improve the sweep efficiency in heterogeneous reservoirs by developing a hybrid workflow that integrates existing tools and methodologies.