Screening a Multi-fractured Horizontal Well Production and Drainage in an Unconventional Reservoir

Abstract

AbstractNowadays, industry firmly establishes the use of fractured horizontals wells for exploiting oil and gas reservoirs. In 2016, hydraulically fractured horizontal wells accounted for 69% of all oil and natural gas wells drilled in the United States. This work investigates the transient well responses of a multi-fractured horizontal well producing an Unconventional Reservoir. The created individual fracture responses originate from an infinitive reservoir and are considered diffusion equation full-time rate responses. The analytical screening process is helpful for prognosis, diagnosis, and improved modeling of hydrocarbon production and drainage. Screening analyses can generate valuable information for fracture diagnosis in addition to a well and fracture production prognosis, mainly when limited input data are available. Multi-fractured horizontal well rate time and pressure time responses represent the solutions to a diffusion equation with varying boundary conditions and fracture options (i.e., various fracture orientations, various fracture lengths, etc.). The well response solutions are analytical and the model screens a horizontal well with multi-fractured productions. The transient model calculates individual fracture rates, productivity indexes, and equivalent wellbore radius. Individual fractures are acid or proppant. Each fracture to a well inflow includes choking pressure effects. This presentation studies the transient decline, emphasizing a horizontal well with fracture wellbore responses positioned in Unconventional Reservoirs. We want to find out the most optimal number of fracture stages and support management in quickly making fast decisions, mainly when most G&G and reservoir data are limited or unavailable for a complete reservoir flow simulation study. To optimize a horizontal well production rate, we investigate the most significant effect of a reservoir, fracture, and well on such wells’ productivity. Further, we use an analytical model that quickly assesses the impact of various well or reservoir properties on well performance. The model is three-dimensional, heterogeneous, and considers full-time rate–pressure time solutions. It assumes single-phase flow and fractures positioned on a horizontal well are transverse or longitudinal of varying types (uniform flux, infinite conductivity, finite conductivity). We use various constraints and multi-run sensitivity for the prognosis of multi-fractured horizontal well productivity and its diagnosis. For screening and optimization of a multi-fractured horizontal well, we use a fast and robust numerical algorithm. This paper investigates a horizontal well-fractured design and proposes the most optimal number of created transversal fractures economically valuable. A semi-analytical screening efficiently generates rate–pressure time monophase transient wellbore responses. Such wellbore responses complement finite differences multi-phase model solutions that handle heterogeneous and complex geometry but include numerical dispersion when solving partial derivatives with the algebraic equation. The study estimates hydrocarbon production profiles for various fractures, including the most optimal fracture number (fracture height, fracture half-length, fracture conductivity). Further, it provides a workflow for optimizing a fractured horizontal well production and drainage with the risk assessments in an Unconventional North Sea Reservoir.KeywordsMultilateral fractureHorizontal wellSemi-analyticalFlow simulationsProppant fracture