24X7 Monitoring During Long Term Testing Using Multiphase Flow Meter In HPHT Exploratory Well Located In Remote Area - A Case Study.
Authors: Subban Packirisamy , Al-ibrahim Abdullah Reda , Rajkhowa Anupam 
Published: March 2015

This paper presents a case study of Long Term Testing (LTT) performed using Multi Phase Flow Meter (MPFM) first time in Kuwait in HPHT sour environment to evaluate the potential of the newly discovered reservoir. An accurate measurement of multiphase flow is a complex task due to various unknowns involved. The conventional technique of gas/oil separator needs frequent personnel intervention and does not provide full solution making the LTT a costly affair. A direct measurement of multi phases using MPFM in the production flow resulted into a large savings.

Understanding the various parameters including reservoir potential, boundaries and dynamic fluid flow behavior are crucial through LTT before the field is committed for development. Acquisition of well production data more frequently from a remotely located well during LTT in the sour and extreme conditions of wells is always been a problem, which is compounded with the absence of facilities in the nearby area. Different options were studied to choose the best methodology for monitoring the phase flow in newly discovered wells during LTT. MPFM was chosen over conventional method for conducting LTT as they can record the flow parameters continuously on 24x7 basis, which is vital for pressure transient analysis and well performance optimization in newly discovered reservoirs.

The implementation of LTT warranted modifications at flow lines near wellhead to install MPFM and accessories to acquire and transmit well and fluid flow data on continuous basis through satellite. Multi-choke flow test and pressure build-up survey were conducted for pressure transient analysis.

Use of MPFM helped in recording parameters such as Gas, Oil & Water flow rates, flow line pressure & temperature, identifying well flow problems and understanding reservoir behavior. It helped in addressing the problems like tripping of Surface Safety Valve (SSV) on 24X7 basis that avoided Non Productive Time (NPT) on these wells. Continuous data collected during LTT period helped in evaluating the potential of the reservoir and understand its long term production capability with more confidence over the conventional method. The MPFM were pilot tested in two HPHT wells and the data collected were analyzed with excellent results.

Introduction

An exploratory well in this structure was drilled to explore the hydrocarbon potential from Najmah, Sargelu and Marrat formations on the west central flank of the field which is located in South Kuwait area. This is totally new prospect at Jurassic level which is far away from Jurassic wells drilled and tested in Eastern part of the oilfield.

Marrat formation in this well was perforated underbalance and tested with DST tools. After acid stimulation, the well successfully produced good quality oil of 42oAPI and gas with 3.5% H2S from the deep and fractured carbonate reservoir. Completion diagram of this well is shown in Fig-1.

This discovery test confirms a potential of light oil & gas in the structure of East Kuwait fields. In order to understand reservoir characteristics, long term deliverability of a reservoir and formulate a delineation/ development plan, it was necessary to go for a Long Term Testing (LTT). The sour nature of the oil & gas in this well warranted to connect this well with the nearby sour production facility. This well is located far away from the existing sour production facility which is located in West Kuwait and a long flow line was required for conducting LTT.