Dynamic modelling and real-time monitoring of intelligent wells

Intelligent Wells (I-Wells) are the wells equipped with in-well Flow Control Devices (FCDs) and sensors. I-Wells offer a wide range of flow control and monitoring options, with the latter often being subject to how well the information is derived from the measured, raw data. Pressure or temperature are the measurements most commonly taken and requiring interpretation in I-Wells. This work develops innovative methods for modelling and monitoring of dynamic, transient flow in I-Wells. The topics cover: i. I-well clean-up modelling and analysis; ii. Integrated Pressure and Temperature Transient Analysis (PTTA) in wells; and iii. Pressure Transient Analysis (PTA) in I-Wells. This study starts with addressing the challenging clean-up process in I-Wells. A dynamic, coupled wellbore-reservoir modeling workflow is developed that simulates the whole process from fluid invasion to the flow back period. This is followed by investigating the role of different types of FCDs, e.g. autonomous and passive FCDs, well geometries etc. on the cleanup efficiency. General recommendations to facilitate the clean-up in I-Wells are further provided. This study continues with a novel methodology integrating mature PTA solutions with the relatively new Temperature Transient Analysis (TTA) ones for various applications such as reservoir characterization, flow rate allocation and completion monitoring. Several available TTA solutions are extended to describe the multiphase flow in the reservoir. The required modifications and workflow are developed and verified using synthetic case studies. The value of the integrated analysis is then demonstrated by presenting a new method applicable for multi-phase production rate allocation in multi-zone, vertical I-Wells. The variable rate problem in the TTA context is later studied where the distorted signal is reconstructed by proposing normalization methods and developing a data-driven deconvolution algorithm. Finally, the effect of non-linear pressure drop across FCDs in I-Wells on applicability of the classical PTA solutions is investigated. The corrections to incorporate this effect into the classical PTA solutions is implemented as well as a workflow to decompose the total skin is presented. The value and applicability of the proposed workflow are later illustrated using real field case studies. This thesis is an important contribution into the understanding, modelling, monitoring and analysis of dynamic flow process in advanced wells

Pressure transient analysis in advanced wells completed with flow control devices

Abstract Inflow Control Devices (ICDs) modify the inflow profile of a multi-zone well completion. Their imposition of an extra pressure drop at the sandface has proven to be particularly effective at delaying the breakthrough of (unwanted) water or gas in wells with long completion lengths. It is widely accepted that an ICD completion improves the field's economics; but the question of whether and why an ICD completion affects the accuracy of standard Pressure Transient Analysis (PTA) workflows has not been addressed. A typical ICD completion is designed to create an extra pressure drop of a similar magnitude to the well's expected reservoir drawdown when producing at its target rate. This paper shows why this extra pressure drop cannot always be treated as an additional skin value during PTA. This is because the ICD's pressure drop is a time dependent variable, varying with both fluid's viscosity and flowrate through the device. A nonlinear pressure loss can, sometimes, distort the pressure response and render conventional PTA methods inaccurate. The study presented in this paper uses an integrated, dynamically coupled, wellbore and reservoir model to define the limits within which treating the ICD pressure drop as an additional skin is a valid assumption and when its nonlinear nature will result in an inaccurately estimated value of skin and reservoir permeability. A general workflow for the analysis of PTA data measured in liquid producing wells completed with ICDs is proposed for the derivation of realistic values of the formation damage skin. The workflow has also been adapted for routine monitoring of wells completed with ICDs. The value of this study is illustrated by its application to two data sets from the North Sea's Golden Eagle field. This is an ideal field to test the validity of our theoretical analysis due to well completions with multiple levels of inflow control together with "state-of-the-art", downhole sensors. The results of this work allows Reservoir and Production Engineers to differentiate between deteriorating well performance due to increasing watercut and that due to an increasing formation damage skin.</jats:p