Understanding the Roles of Inflow-Control Devices in Optimizing Horizontal-Well Performance

Abstract

Abstract Inflow Control Device, often referred to as equalizer, is a completion hardware that is deployed as a part of well completions aimed at distributing the inflow evenly. Even though the detail structures vary from one design to another, the principle for different inflow control devices is the same - restrict flow by creating additional pressure drop, and therefore balancing or equalizing wellbore pressure drop 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, sand production and solve other drawdown related production problems. In general, inflow control devices 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 inflow control devices extremely critical for production. Inflow control devices can be either beneficial or detrimental to production, strongly 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 inflow control device is a function of time. The inflow control devices sometimes can be overlooked if the design is only based on reservoir flow simulation. In this paper, we will investigate how and when an inflow control device 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 inflow control devices will be considered. Two conditions that result in production problems, wellbore pressure drop and breakthrough of unwanted fluids, will be addressed. The focus will be on when and how an inflow control device can optimize production. Examples at field conditions will be used to illustrate that it is critical to understand the reservoir conditions and wellbore dynamics together when designing a well completion with inflow control devices. Since uncertainty of reservoir condition always exists, backup plans and conservative designs are desirable. The observations from this study show that overdesigned inflow control devices will not just increase the cost of well completion, but also impact the well performance negatively. Introduction With advances in drilling technology over the past 30 years, horizontal and multilateral wells have become a primary design type to develop reservoirs, especially in unconventional resources. The need to produce efficiently, economically and environmentally-friendly has promoted the development of extended reach horizontal and multilateral wells which enable greater reservoir contact and lower draw-downs to achieve similar rates as conventional wells. However this increased wellbore length has led to some problems in producing from such a well. Higher pressure drawdown around the heel section as a result of frictional pressure drop of fluid flow in the wellbore causes non-uniform fluid influx along the length of the wellbore and higher production rates at the heel. This often leads to early break-through of water or gas, which causes a reduction in oil recovery and uneven sweep of the drainage area. With longer contact between reservoirs and wellbore, heterogeneity is more likely encountered, and permeability contrasts along the wellbore can also result in the same phenomena because of unevenly distributed pressure along the wellbore.