PRODUCTION LOGGING. INTRODUCTION: New Tools and Techniques for More
. Accurate Logging in Horizontal and Deviated Wells. Center-Sampling Tools ...
PRODUCTION LOGGING
Production Array Log Interpretation Complete, Customized Interpretation Supports Better Intervention
INTRODUCTION: New Tools and Techniques for More Accurate Logging in Horizontal and Deviated Wells
Analyzing Flow Rates, Volumes, Fluid Entry/Exit Points In these conditions, standard center-sampling devices cannot accurately quantify distributions and velocities. They produce incorrect volume estimates and misdiagnose fluid entry or exit points. This makes it difficult to optimize production. The problem becomes worse as wells approach horizontal and their paths begin to undulate. Finding the source of water production with center-sampling tools in these conditions can be difficult or impossible. Due to the tool’s location in the wellbore, the sensor may not fi nd the fluid in the zone that is producing it. Multisensor Tools Sample All Phases of Production Accurately To remedy this problem, a new generation of tools senses fluids and flow rates across the wellbore. Multiple sensors in Halliburton’s new Capacitance and Spinner Array Tools accurately log the entire cross section of horizontal and deviated wells over the entire zone – even if the orientation of the tool varies. In multizone wells, Halliburton’s new tools can identify the flow rates and volumes of each fluid at each stage. This makes it possible to quickly determine the source of water production and take remedial actions that increase production of oil and gas, and extend the life of the well. Need for Specialized Logging Software & Expertise Because these tools are so new, few people know how to interpret logs they produce. Accordingly, Halliburton offers interpretation as a service using specialized, proprietary software. This software integrates data provided by traditional sensors with the newer arrays, then outputs the results into Kappa’s industry-leading Emeraude® package, resulting in a comprehensive analysis in an easy-to-read log format. This allows engineers to easily develop intervention programs that truly address production issues.
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Center-Sampling Tools Misdiagnose Horizontal Wells In vertical wells, oil, gas and water remain uniformly distributed across the wellbore. However, when wells deviate more than 20 degrees from vertical, fluids begin to separate into their own streams and move at different rates. Lighter fluids move along the high side of the well, heavier fluids along the low side.
Avoiding Costly Mistakes This horizontal well was producing 600 barrels of hydrocarbons and 15,000 barrels of water per day. Our log clearly showed all hydrocarbons were coming from the zone at the far right. Traditional center-sampling tools could not see where oil and gas were coming from. The client’s reservoir model suggested that oil should have been coming from Zone 2. After setting a bridge plug to block off Zone 1, the well started producing 1,500 barrels of oil and 600 barrels of water per day. The higher pressure from Zone 1 had not been allowing the hydro-carbons to enter from Zone 2.
Production Array Log Interpretation Compared to traditional tools with a single, centered sensor, Halliburton’s multisensor Capacitance Array Tool (CAT) and Spinner Array Tool (SAT) offer several features that provide important benefits. Features • Multiple sensors along with tool rotation and relative bearing measurements increase wellbore coverage • Processed data easily shared between Halliburton and clients using Emeraude® features • Interpretation options based on data availability and quality • Linked with Kappa Emeraude to provide seamless processing • Horizontal and vertical displays showing phase segregation • Allows three dimensional imaging with Halliburton software.
PRODUCTION LOGGING
Benefits • Accurate holdup and velocity measurements at any inclination
Halliburton’s array sensors are well suited for any deviated well analysis. They can identify and quantify fluid fallback. This improves understanding of the contributions of individual zones to the total flow. It also helps identify thief zones where valuable fluids may be escaping before reaching the surface.
• Downhole flow rates determined independently of slip velocity • TVD displays allow visualization of wellbore undulations and effects on holdups and velocity
Revealing the Precise Sources of Oil, Gas and Water Production
• Links with Emeraude to provide complete interpretation including phase flow rates both downhole and at surface
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• Customized interpretation based on available data: CAT/SAT alone or with other sensors.
In deviated wells, fluid flow segregates into different phases. Lighter fluids move to high side and heavy fluids to low. Sensors in our new generation of array production logging tools provide continuous crosssectional measurements of water holdup (dark blue) and fluid velocities in any wellbore.
Diagnose multizone, multiphase wells better Deviated wellbores with multiple completions are very difficult to evaluate especially when fluids become segregated (see example, above). Zone D shows very high water holdup while Zone C shows increasing oil holdup and the beginning of fluid stratification. As oil holdup increases, lighter hydrocarbons segregate to the high side of the hole while water congregates on the low side. The interface between oil and water may be well defined or irregular depending upon the velocity of the flow. Defining the holdups of each phase is extremely difficult with a centersampling device. Only tools with multiple sensors that measure the entire wellbore can provide reliable measurements; a single centered sensor may not measure each of the respective phases. Identify fluid fallback and thief zones Individual reservoir pressures and parameters along with wellbore pressure determine the velocity of fluids in the wellbore. Depending on the reservoir, there may or may not be water fallback. If there is, fallback influence on the spinner may be severe and provide less than adequate information regarding fluid and phase velocity.
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Advantages of Array Tools Over Center-Sampling Devices In Deviated Wells
Stand-Alone Capacitance Analysis Track 1 shows gamma ray, temperature and pressure, along with the wellbore deviation and relative bearing of Sensor 1. Track 2 shows the average of 12 CAT sensors with fluid density. Right side of track shows water; left shows hydrocarbons. Track 3 displays cross-sectional of six CAT sensors. Blue indicates relative bearing of Arm #1. Length of gray arms indicates type of fluid each arm is measuring – short for water, longer for hydrocarbons. Track 4 is a map oriented from high side to low side back to high side. Lighter fluids should be on high side while water should be in center of track. Track 5 is the vertical presentation of CAT data and is oriented so low side is on left and high on right. The white line indicates wellbore center where center-reading tool strings would be. Heavier water segregates on low side of casing while lighter hydrocarbons flow on high side. Track 6 shows holdups calculated by using vertical segregation of fluids as a percentage of pipe area to provide a more accurate holdup reading. Track 7 shows holdups calculated using the equivalent weight method, thus providing average holdup.
PRODUCTION LOGGING
Providing Accurate Velocity Information
The sensor display shows the relative velocity of the six SAT spinners. At Depth A, we see downflow of fluid on the low side of the casing while positive fluid movement is occurring on the high side. Immediately above this depth there are areas of increasing fluid velocity, followed by a slowing velocity. The CAT log shows corresponding changes in holdups at this depth. Providing Accurate Flow Information on Each Phase
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Combined CAT/SAT: Eliminating the problem of slip velocity between phases Correlating holdup and velocity information shows you actual flow rates and flow directions of each phase for the first time. Together, these logs eliminate the problem of estimating slip velocity between phases. This is a radical step forward in log analysis.
Stand-Alone Velocity Analysis Track 1 shows gamma ray, temperature and pressure, along with the wellbore deviation and relative bearing of Sensor 1. Track 2 shows the average velocity (AVE VA) of six SAT spinners. From these, we calculate the velocity near the center of the wellbore (CENTER VA). This calculated velocity closely follows the inline spinner VA in segregated flow. Track 3 shows arm position and relative velocity of six SAT spinners. Longer arms indicate higher velocities; shorter arms indicate slower velocities (including negative velocity). This shows the highest velocity on the high side of the wellbore with some downflow occurring on the low side. Track 4 presents minimum, average and maximum VA of six SAT spinners.
What This Log Shows
Track 6 shows a cross-sectional view of SAT VAs with low side on left and high side on right. The SAT sees fluid flowing downhole on the low side with positive values on the high side.
Zone A is an example of fluid fallback as seen by the SAT. Correlating capacitance and velocity analyses allows determination of the total flow without relying on slip analysis.
Six Spinners Cover Entire Wellbore Cross Section Halliburton’s Spinner Array Tool (SAT) provides six radial spinner measurements that create a velocity profile of the entire wellbore. The log above shows the standard processed interpretation. Halliburton can customize this based on your needs.
This combination provides the best solutions for horizontal, deviated and multiphase flows including upflow, downflow and possible circulation flow. In this well most of the production is from the perforations at B. This processing simplifies visualization of complicated flows as seen by the segregation of the fluids in both the CAT and SAT vertical displays in Zone C. This improved interpretation will result in better understanding of the behavior of downhole fluids. It will also result in applying the correct intervention program for each specific situation.
What This Log Shows CAT and SAT displays are similar, allowing easy comparisons of both the holdups and velocities in the wellbore.
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Track 5 shows the image created from the six separate SAT velocities. The black (-63) to white (0) indicate negative velocity while yellow (0) to dark brown (225) indicate positive VAs in feet/min. The center of the track shows the low side while the left and right edges show the high side of the wellbore. Notice that the highest downflow is on the low side around X082.
PRODUCTION LOGGING
How This Analysis Saved an Expensive Intervention
Capacitance Array Tool (CAT)
Spinner Array Tool (SAT)
The Value of Combined CAT/SAT Interpretation Halliburton’s CAT and SAT tools are now available together – with an interpretation service – for the first time. This service can tell you precisely where fluids are flowing in your well and at what rates. No longer do you have to rely on estimates produced by slip analysis. Now you can have direct measurements.
Water production in this well caused the owner to consider remedial action. The owner ordered CAT and SAT logs to determine the water’s source. These logs showed that upper perforations were not providing any appreciable fluid entry. Higher pressure at B was forcing water down to A which was acting as a thief zone. Setting a bridge plug below these perforations could have actually increased water production and decreased oil production. The well was already acting as a downhole separator.
The information provided can help improve your reservoir model or fi x a production problem in your well. This information helps avoid costly interventions that may be counter-productive and helps design precise interventions that produce positive results by addressing real issues.
The logging operation saved the cost of a remedy that would have, most likely, been counterproductive.
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Ultimately, this information assists in optimizing production and extending the producing life of your well.
CAT and SAT developed in part through cooperation with Sondex.
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