Technical Feasibility and Applicability of a Concentric Jet Pump in Underbalanced Drilling

Abstract

fax 01-972-952-9435. AbstractWe examine in this paper the feasibility of using a concentric jet pump to create an underbalanced condition while drilling subnormally pressured reservoirs, using only single phase injected fluids, eliminating the need for gas. A complete technical basis for the performance and design of jet pumps for underbalanced drilling applications is presented. The problem is handled in four parts: reservoir to jet pump suction, the jet pump itself, annular flow from jet pump exit to surface, and power fluid flow. Multiphase flow theory, viscous flow theory and jet pump flow theory are used to analyze the problem. The design goal is to find the correct combination of jet pump location, geometry, power fluid density and rate such that the jet pump exit energy is adequate to lift the mixed fluids and solids to surface. Other design considerations such as tolerance of varying reservoir conditions and depth, cavitation, sonic velocity limitations, and power fluid injection pressure constraints, are also taken into account in the design procedure. Jet pump design envelopes unique to its application in underbalanced drilling are developed to aid selection and design of the pump. A design program that implements the procedure has been developed. The procedure is illustrated with two examples: an oil well and a gas well. We find that the jet pump can successfully create an underbalanced state for a wide range of conditions. In general, for reservoir pressures in the range of 4 to 7 ppg equivalent, the jet pump appears to enable creation of an underbalanced condition without requiring injected gas, regardless of whether the reservoir is oil bearing or gas bearing. Operational and practical considerations that need to be addressed in proving the design are also discussed. Based on this work, we conclude that the concentric jet pump is a unique device technically suitable for a wide range of uncerbalanced drilling applications.

Simulation of asymmetrical rotational flow in the flow part of a well jet pump

“…Дослідженням робочого процесу струминного насоса за допомогою даних аналітичних співвідношень встановлено, що оптимальне значення коефіцієнта інжекції ежекційної компоновки дорівнює одиниці. Компанія Blade Energy Partners [2] розробила математичну модель робочого процесу наддолотної ежекційної системи, що складається з декількох концентричних напірно-всмоктувальних струминних насосів, із залученням класичних рівнянь Бернуллі, Дарсі-Вейсбаха та суцільності змішуваних потоків. Промислове підтвердження розробленої на основі класичних законів гідромеханіки методики визначення характеристик наддолотного струминного насоса дає змогу рекомендувати її використання для обґрунтування вибору режимів експлуатації вибійних компоновок призначених для "збалансованого" буріння.…”

Numerical and experimental investigation on the depressurization capacity of a new type of depressure-dominated jet mill bit

“…The jet pump was introduced in the oil-and-gas industry in 1970 and widely used for underbalanced drilling (Zhu et al 2013;Yang et al 2012). There were many kinds of tools for underbalanced jet-pump drilling, such as an annular jet-pump depressure joint (Hooper 1986), a jet-pump bit (Lott 1998), an annular jet pump fixed inside casing (Suryanarayana et al 2004;Hughes 2005), an annular jet pump with drill string rotation (Hosie et al 2005), and so on. However, all these tools' depressurization capacity is limited as the jet pump is far from the bottom hole and there is always a big clearance in annulus.…”