An Investigation of the Economic Benefit of Inflow Control Devices on Horizontal Well Completions Using a Reservoir-Wellbore Coupled Model

Abstract

Abstract A finite-difference, lumped-parameter based, reservoir-wellbore coupled model was developed to characterize the economic benefit of inflow control devices on horizontal well completions. Baker Oil Tools' inflow control device (ICD), the Equalizer™, has been tested and analyzed as a standalone entity. Several correlations have been developed to quantify the pressure drop characteristics of this ICD. To show the positive effects an ICD has on an asset, one must quantify, not only the flow performance of the ICD, but the time dependent depletion scenarios of the reservoir in question. In this paper, the benefits of a unique inflow control device will be shown by analyzing reservoir depletion scenarios with and without inflow control. Without inflow control, a horizontal completion is at risk of early water breakthrough. With early water breakthrough, the water cut tends to escalate due to its lower viscosity compared to that of oil. As the water cut escalates, oil production drops significantly, often leading to shutdown of the well and reserves being left in the ground. This paper will show the benefits of using an ICD by describing the model development of a hypothetical, yet typical, field and the subsequent analysis that drives the completion design of the horizontal well. The model includes the reservoir, water oil contact, near-wellbore characteristics, wellbore, sand control screen, ICDs, basepipe, and production tubing, capital expenditure input, and real time calculations of net present value of the reservoir. The use of inflow control devices increases the capital expenditure, but the increased cost is more than compensated for by the increased production efficiency. The technology presented can be extrapolated and applied to the analysis of well completions consisting of different types of hardware. Future developments of this type of analysis will be described. This work provides three additions to the technical knowledge base of the petroleum industry; 1) use of a lumped-parameter finite-difference based model to couple the wellbore completion to the reservoir, 2) proof of the positive effects of inflow control devices on producing hydrocarbons, and 3) further information on using the "economics of reservoir depletion" to drive horizontal completion designs. Introduction Horizontal wells have become an established method of recovery for oil and gas. In reservoirs where these fluids occupy strata that are horizontal, or nearly so, a horizontal well offers greater contact area with a productive layer than does a vertical well. Larger contact areas allow lower drawdowns to recover more oil or gas. Economics aside, these facts imply that a horizontal well should be as long as possible. However, frictional effects in the wellbore limit the useful length of a horizontal well.1 Frictional effects can be significant in long horizontal wells in high permeability reservoirs. In such cases, the drawdowns are low and they are of the same order of magnitude as the frictional pressure drop in the well. If wellbore pressure drop is not taken into account in such cases, the productivity of the well can be grossly overestimated. Wells in reservoirs with an aquifer and/or gas cap face the risk of early breakthrough of water or gas. Ignoring wellbore pressure drop would make the engineer assume that the encroachment of water/gas is uniform towards the horizontal well along its entire length. But in reality, encroachment is skewed and fluids tend to break through first at the heel of the well. The only way to quantify those effects is by including the wellbore pressure drop in the calculations.2 The phenomenon of uneven flow distribution in the reservoir caused by frictional pressure drop in a horizontal well can be seen in Figure 1.