Magnetic Resonance for the Future; A New Methodology to Measure Multiphase Flow

No multi-phase flow meter is currently available on the market that can be installed on well heads and satisfies the need of the energy sector in terms of accuracy across a broad range of produced volumes and hydrocarbon properties and operational robustness. Consequently, a large number of oil-field installations are either insufficiently metered or rely on accurate, yet costly and operationally cumbersome test separators. Insufficient metering may result in suboptimal reservoir management and uncertainty in allocation of co-mingled production.

This presentation describes a joint development of Krohne and Shell that targets provision of highly accurate, real-time quantification of flow rates for oil, water, and gas in multiphase flow using Magnetic Resonance Technology. Magnetic Resonance is intrinsically sensitive to flow; however, current applications to flow measurement are limited to very low flow rates that are inapplicable to oil-field applications. The Shell-Krohne development employs a new principle that enables robust 3-phase flow metering with a broader operating envelope than existing flow meters, has no sensors in the flow stream, no radioactive source, yet can be produced at sufficiently low cost to promote increasing numbers of well head installations.

Multiphase Pumps for High Pressure Applications

Following safety rules of the oil & gas industry, multiphase pumps have to be designed according to the pressure rating of the connected pipelines. In case of pressure ratings exceeding 100bar, alternative concepts become more attractive from technical and commercial point of view. This paper discusses different technical concepts for multiphase pumps, starting with the normal Multiphase Pump Compressor (MPC) for up to 100bar, going to the Multipurpose Twinscrew Machine (MTM) with a 150bar pressure rating to the Canned Multiphase Pump Cartridge (CMPC) which can be built to fulfill most requirements, typical ratings are 350 bar, 500bar and 1000bar. The high pressure pumps are new devlopments, based on the experience with subsea technology. High pressure rating, high differential pressure and very long MTBF intervals are some of the special features, taken from the subsea pumps (SMPC).

A new Multiphase Header Design – Fluid Distribution in Multi-Pump Operation

Parallel operating multi-phase pumps interact due to hydraulic coupling. Asymmetrical distribution of the multi-phase mixture can then lead to an uneven working load in parallel operating multi-phase pumps. Thus the operating range of the complete pump system is limited by the marginal operation of individual pumps.
Homogenization of the flow conditions can make the operating range of a pumping system with parallel operating multi-phase pumps fully usable. For this purpose a specific header design was examined, the fundamentals of which are discussed and initial operational experiences are described.

Operating Experience with Diamond Coated Seals

Single mechanical seals with hard/hard face combination and with a non-pressurized quench are a cost-effective and low-maintenance seal system for multiphase pumps, which have to deal with a high content of gas and solids.
In multiphase applications silicon carbide seal faces are limited to low pressure differences, due to insufficient lubrication of the seal faces at a high gas volume fraction (GVF). DiamondFace® seals have an excellent performance under poor lubricating condition and thus can deal with an increased pressure differences even at high GVF’s.
A twin-screw multiphase pump was equipped with four single DiamondFace® seals in order to check the seal performance at high pressures and high gas contents. After 150 h of operation at 24 bar sealing pressure and 95% GVF and after 50 Start/Stop the seals have been inspected. All seals passed the test with an acceptable operating performance and without any signs of degradation.

 An overview of pressure boosting capabilities within the transient multiphase flow simulator OLGA 7

The transient Multiphase Flow Simulator OLGA 7 was released in September 2012. The paper will elaborate on a number of case studies demonstrating the applicability for Twin-Screw Multiphase Pumps.

Research & Development

Properties of Selected Pump Shaft Materials for Multiphase Applications

In multi-phase applications predictable equipment reliability is of great importance to keep maintenance costs as low as possible. The pump shaft as a rotating part is a key element in this regard. Mechanical loads act together with corrosive attack. Both, the mechanical and the chemical requirements increased markedly with the introduction of multi-phase pump technology.
In a joint project between Bornemann and Schmidt + Clemens environmental corrosive conditions have been collected and mechanical loads on the pump shaft identified. On the materials side a process has been defined to select materials, which meet these requirements.
Three materials and their properties are described in more detail, because they have been selected as candidate materials. They are most likely to withstand for long times even in subsea applications.

Development of a Corrosions-Sensor for Multiphase Transportation Systems

The conference paper will describe the development of a new, two electrode corrosion sensor for the use in multiphase transportation systems. A critical overview will be given as to the current state of the art of commercial corrosion sensors, pros and cons will be discussed. A short introduction to sequence dependent and sequence independent signal processing will be given to show how different corrosion types such as general corrosion, pitting corrosion and crevice corrosion can be identified. The principle design of the sensor will be presented in two versions, as well as the flow loop used for testing and the monitoring software for the data analysis.

Fatigue Strength of Multiphase Pump Components under the Influence of Pitting Corrosion

In extremely corrosive environments a corrosive attack of pump-components, i.e. by corrosion pits, might take place. A reduction of the pump-component's fatigue strength is the consequence of the attack.  This paper presents a new method to incorporate the effects of corrosion pits in the analytical strength assessment, in order to build the pumps more efficient and reliable for these operating conditions. The proposed calculation method is verified using a series of fatigue tests with pre-corroded specimen.

Pressure Build-Up and Pulsations in Twin-Screw Multiphase Pumps Conveying Oil and Gas

The performance of twin-screw multiphase pumps is well-known for common mixtures of water and air. When conveying other fluids, their physical properties have to be taken into account as they gain influence on the conveying characteristic. The pressure build-up within the pump changes depending on the solubility of gas in oil. Although twin-screw pumps are known as continuous conveyors, pressure pulsations emerge in the outlet of the pump.


 A review on mathematical modeling and experimental procedures

The increasing requirements on the performance of multiphase pumping systems combined with those related to a higher operational availability of such systems, as well as operating conditions with pressure increase of about 150 bar, highlights the importance of developing accurate mathematical models to predict the performance behavior of these equipment.

This paper, by performing a fairly comprehensive literature search, presents a review of the found mathematical modeling and experimental procedures to predict the thermo-hydraulic behavior and performance of multiphase pumping systems based on twin-screw pumps. Mathematical models to predict multiphase flow characteristics, pressure drop in narrow rotating annular clearances, pressure distribution and build up along pump chambers, back flow and heat transfer through rotors and casing are described and discussed.

Experimental procedures to evaluate pressure and temperature distribution as a function of gas void fraction, inlet and discharge pressure and rotating speed are summarized and compared. Also experimental studies of the dependence of flow rate with pressure difference and gas void fraction are taken into account.




Overcoming High Pipeline Backpressure Caused by Hilly Terrain in Southern Italy

During the last three years several multiphase boosting installations have been realized in ENI Val D’Agri field in Southern Italy, by the contracting company Italfluid Geoenergy Srl.
Experience was gathered from the first test with one medium size multiphase pump, installed at a single well, to an application with a very large one that gathers flow from different wells.
This presentation will highlight the increased oil recovery and the general flow stabilization inside the flow lines, despite the complex topography of the area.

Implementation of Multiphase Pumping Systems in Fields of the AIATG

The PEMEX reservoirs of the fields at Activo Integral Aceite Terciario del Golfo (AIATG) are stratified, lenticular, heterogenous and discontinuous sands with a pushing mechanism by means of disolved gas, low-productivity-index wells and fast depletion rate. These conditions pose a great challenge for the implementation of the multiphase pumping technology taking into account its dynamic conditions.

A technological demonstration was realized using a twin-screw multiphase pumping system in one of the production pads. The results demonstrated the feasibility of using the technology to extend the operation life of the wells as well as increasing the production of hydrocarbons.

Operational Experience with Large Multiphase Pumps in Difficult Topography

Petroamazonas EP, nowadays the only national oil company from Ecuador, has installed in 2010 the first multiphase pumping system application in the country, prioritizing the environment over facilities expansion or other variables as a result of a risk mitigation plan. In this presentation there will be a review of our operation experience from the startup, the current operation, a comparison between the current operation conditions and the design conditions, problems and failures, action plans implemented, and some lessons learned from the entire experience.  The operation experience for the first time in Ecuador has given good results for the goal they were designed, anyway the failures in the system have affected the expectation of the project. At this time problems have been overpassed and system is running with a good performance.

Parallel Installation of Multiphase Pumps in Rajasthan-India

Cairn India Limited the largest producing oil field in the Indian private sector and has pioneered the use of cutting-edge technology to extend production life. Cairn India holds material exploration and production positions in 11 blocks in west and east India along with new exploration rights elsewhere in India, Sri Lanka & South Africa.

Cairn India’s Rajasthan Onshore field is the largest hydrocarbon discovery in the last 25 years and currently producing at the rate of 175000 BOPD from its Mangala, Bhagyam & Ragheswari fields and Aishwariya field is joining to commence Production from this month. Last year, 4 units of Multiphase Pumps have been commissioned at Bhagyam field for transporting the Bhagyam field well fluids & gas to Mangala Process Terminal, thru 24” size x 25 KM long underground piping for the common processing & Oil export. These Pumps are specially designed for Pressure boosting application from 1 bar to 13 bar with symmetric flow assurance inlet & outlet piping and compact Skid arrangement for easy transportation & installation. My Presentation in EMBT Conference will cover the “Successful installation, commissioning and one year of Operation at varying operating condition” of handling different composition of oil, water & gas from Bhagyam onshore wells and will share the O&M challenges faced over the period of one year.