Impact of Completion Design on Fracture Complexity in Horizontal Wells

Abstract

Abstract A proppant-filled fracture induces mechanical stresses in the surrounding rock causing a reduction in the stress contrast and stress re-orientation around the open fracture. A three-dimensional geo-mechanical model is used to simulate the stress reorientation due to open fractures and generate the stress contrast contour maps. The reduction in stress contrast can lead to increased fracture complexity. This paper describes how fracture complexity can be increased by varying the completion design. In this paper, we identify the impact of operator-controllable variables in a completion design on fracture complexity. This can lead to more effective completion designs that improve well productivity, reservoir drainage and ultimately EUR. The possibility of greater fracture complexity and reduced effective fracture spacing and hence higher drainage area is demonstrated for an alternate fracturing sequence in comparison to the conventional fracturing sequence. The Young's modulus value of the shale and the in-situ horizontal stress contrast are shown to be significant factors controlling the extent of fracture complexity generated in a given reservoir. In addition, the effect of proppant mass injected per stage and the fluid rheology is also shown to significantly impact fracture complexity. We provide optimum ranges of fracture spacing, proppant volume and fluid rheologythe various formations analyzed. The use of these guidelines should result in more fracture complexity than would otherwise be observed. The results presented in the paper allow an operator to design completions and fracture treatments (rates, fluids, fracture spacing and sequencing) to maximize reservoir drainage and increase EURs. This will lead to more effective completion designs.