Understanding the roles of inflow-control devices in optimizing horizontal-well performance
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An inflow-control device (ICD) is completion hardware that is deployed as part of well completions aimed at distributing the inflow evenly. Even though the detailed structures vary from one design to another, the principle for different ICDs is the same-restrict flow by creating additional pressure drop and therefore adjusting wellbore pressure distribution to achieve an evenly distributed flow profile along a horizontal well. With a more evenly distributed flow profile, one can reduce water or gas coning, prevent sand production, and solve other drawdown-related production problems. In general, ICDs are not adjustable; once installed in the well, the location of the device and the relationship between rate and pressure drop are fixed. This makes the design of a well completion and ICDs extremely critical for production. ICDs can be either beneficial or detrimental to production, depending on the reservoir condition, well structure, and completion design. Realizing that reservoir conditions will change during the life of a well, the impact of an ICD is a function of time. Reservoir heterogeneity and uncertainty can complicate the situation easily. The ICDs sometimes can be overlooked if the design is based only on reservoir flow simulations at initial conditions. In this paper, we will investigate how and when an ICD should be used. An integrated analysis method of inflow (reservoir) and outflow (wellbore) is used to generate the flow profile of a horizontal well, and additional frictional pressure drop created by ICDs will be considered. Two conditions that result in production problems, wellbore pressure drop and reservoir heterogeneity, will be addressed. The focus will be on when and how an ICD can optimize production. Examples will be used to illustrate that it is critical to understand the reservoir conditions and wellbore dynamics together when designing a well completion with ICDs. The observations from this study show that overdesigned ICDs will not just increase the cost of well completion, but also will impact the well performance negatively. ICDs are not a universal solution of production problems. The application requires a thorough understanding of long-term reservoir behavior and upfront reservoir characterization for implementation. Copyright 2011 Society of Petroleum Engineers.
