Pump capacity determination for two-phase vertical fluid flow

Project Abstract

Determining the pump capacity for two-phase vertical fluid flow systems is crucial for various industrial applications, including oil and gas production, geothermal energy extraction, and nuclear power plants. Two-phase flow refers to the simultaneous flow of liquid and gas phases within a pipeline or conduit. In vertical systems, the flow behavior is influenced by gravity, pressure differentials, and fluid properties, making accurate pump capacity determination challenging. This research project focuses on developing a comprehensive methodology for determining the pump capacity required for efficient two-phase vertical fluid flow. The study considers factors such as fluid properties, flow regime transitions, pressure drop calculations, and pump efficiency to optimize system performance. The objective is to provide engineers and designers with a reliable tool to size pumps accurately for two-phase vertical flow applications. The methodology proposed in this study involves a systematic approach that integrates theoretical analysis, empirical correlations, and computational fluid dynamics (CFD) simulations. By combining these methods, the research aims to account for the complex interactions between the liquid and gas phases in vertical flow systems. The analysis considers the impact of flow regime transitions, such as bubble slug flow, annular flow, and stratified flow, on pump capacity requirements. To validate the proposed methodology, experimental tests are conducted using a test rig that simulates two-phase vertical flow conditions. The test rig allows for the measurement of pressure drop, flow rates, and pump performance under various operating conditions. The experimental data is used to calibrate and validate the theoretical models and correlations developed in the study. The results of the research provide insights into the factors influencing pump capacity determination for two-phase vertical fluid flow systems. The methodology offers a systematic approach for engineers to size pumps accurately based on the specific requirements of a given application. By accounting for flow regime transitions and fluid properties, the proposed methodology enhances the efficiency and reliability of two-phase vertical flow systems. Overall, this research contributes to the advancement of pump capacity determination for two-phase vertical fluid flow applications, offering a valuable resource for engineers and designers in various industries. The methodology developed in this study can aid in optimizing system performance, reducing energy consumption, and enhancing operational safety in vertical flow systems.

Project Overview

<p> </p><p><strong>INTRODUCTION</strong><br><strong>1.1 BACKGROUND OF STUDY</strong></p><p>In the production system, Pressure drop has been a major issue in the field. These pressure drops could be experienced as a result of valves and fittings</p><p>installed, due to friction along pipe sections or in lifting fluid up to a certain level.</p><p>As these pressure drops are identified, and the economic flow rate of a reservoir fluid is known, pumps may be employed to reduce the effect of pressure drop and maintain a given fluid flow rate for good economic recovery. These pump applications are usually analysed to determine an optimum Hydraulic pump requirement for a given fluid system and pipe diameter. It can form one of the basic aspect to be considered during well completion in selecting production tubing diameter.</p><p>In general, a pump is a device used to transport liquids, gases, and slurries. However,the term pump is usually used to refer to liquid handling equipment. The purpose of the pump is to provide a certain pressure at certain flowrate of a process stream. The pressure requirement is dictated by the process andpiping involved, while the flow rate is controlled by the required capacity in thedownhole units.</p><p>At least one out of every 10 barrels of oillifted in the world’s oil and gas operations are produced using an ElectricSubmersible Pump (ESP). Typical installationsproduce liquids in the 2,000 to 20,000 bpd range,making the ESP an effective and economical meansof lifting large volumes of fluids from great depthsunder a variety of well conditions.</p><p>There are several types of pumps used for liquid handling. However, these can bedivided into two general forms: positive displacement pumps (including reciprocatingpiston pump and the rotary gear pump), and centrifugal pumps. The selection of thepump type depends on many factor including the flow rate, the pressure, the nature ofthe liquid, power supply, and operating type (continuous or intermittent).</p><p>The power requirement for a mechanical system, like pumps and compressors, isgiven by the general mechanical balance equation:</p><p>P = -mWs = m &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 1.1</p><p>All terms in this equation take their normal meaning with <em>m </em>being the mass flow rate,and α a coefficient used to take into account the velocity profile inside the pipe (forlaminar α = 0.5, while for turbulent α = 1). The required work (or power) given by <strong>P</strong>is the total work that needs to be delivered to the fluid. This work will be drawn froma motor (operated with electricity or engines). The conversion between the motor andpump power is not complete and an efficiency is defined to describe the powerconversion. The efficiency is given by:</p><p>1.2</p><p>The input power can be measured from the source. For example, if the pump is</p><p>operated with electricity, the input power will be <em>I</em>×<em>V </em>(current times voltage). Theoutlet power can be determined using Equation (1.1).</p><p>1. Static head (Δ<em>z</em>term): the height to which the fluid will be pumped.</p><p>2. Pressure head ( term): the pressure to which the fluid will be delivered (ina pressurized vessel for example). The pressure units must be converted to lengthunits using relation.</p><p>3. System or dynamic head (<em>F </em>term): the energy lost due to friction in pipes, valves,fittings, etc.</p><p><strong>1.2 STATEMENT OF THE PROBLEM</strong></p><p>It is important to accurately predict the pressure drop accross a production system. This has been a difficult task in the oil and gas industry as the production system in real life is not homogenous (single phase) as assumed in most theories. The reason for this is that the two-phase flow is complex and difficult to analyze. Ideally, gas moves at a much higher velocity than the liquid. As a result, the down hole flowing pressure of the liquid-gas mixture is greater than the corresponding pressure corrected for down hole temperature and pressure and this could be calculated from the produced gas-liquid ratio.</p><p>This pressure drop in a flowing (production) system could be identified using different existing correlations. Some of these correlations are empirical, mechanistic or numerical. Hagedorn and Brown is the most widely used correlation for vertical wells (Schoham, 2006). In planning well completion the tubing diameter that will give less pressure drop hence much liquid production can be selected by the use of multiphase correlation.</p><p>It is also very necessary to plan for pumps in tubing size selection should need arise on future production for pumping of the reservoir fluid to optimize production.</p><p><strong>&nbsp;1.3 OBJECTIVE OF THE STUDY</strong></p><ul><li>Determine the Hydraulic Horse Power Requirement needed to maintain production of reservoir fluid within economic limit.</li></ul><p>The above objective can be achieved by using two-phase pressure drop correlations to determine pressure drop in selected production tubing used in the Niger Delta.</p> <br><p></p>