Downhole Diagnostic diagnoses your downhole! I use a Fluid Level Gun and a Dynamometer (Dyno) [metaphorically depicted above] to determine the fluid level and measure the downhole pump performance on Rod Pumped Wells. To be more precise, Dynamometers are only applicable to Rod Pumped wells while Fluid Level Surveys can be used on any type of producing oil or gas well that doesn't have a Packer (Fluid Level Shots can even be taken down the tubing, for example: if a tubing leak is suspected). I then submit my findings in a concise report along with any optimization recommendations.
A Well’s Producing Performance (or "Producing Efficiency") is Composed of Two Parts:
The Production Efficiency (or Reservoir Drawdown Efficiency) - can be determined with the Fluid Level Survey (using Vogel's IPR relationship by determining the Producing & Static Bottomhole Pressures).
The Operational Lifting Efficiency (how effectively the fluid is being pumped to surface) - is measured by the Dynamometer.
Take a gander through the information below to learn more about Fluid Level & Dyno Surveys and don't hesitate to call with any specific questions you might have.
Below is a brief description of my diagnostic tools followed by a section on my services and pricing. Click on the header image for each of the diagnostic tools to find a more thorough explanation of how they work along with example reports.
Fluid Level Survey
In its essence, an Acoustic Fluid Level Survey determines the depth to the Fluid Level by generating an Acoustic Pressure Pulse (or Wave) that travels down the well, reflects off the Fluid Level, and then returns back to surface where it is recorded by a sensitive internal microphone inside the Fluid Level Gun. The longer it takes for the wave to reflect back to surface, the deeper the fluid level. The microphone also records other “disturbances” and reflections of the Acoustic Wave that result from the wave encountering tubing collars, a TAC, perforations, or other changes to the cross-sectional area of the annulus. The plot of the acoustic reflections recorded by the microphone is known as the Acoustic Trace (shown above). The shot is generated on the left side, the kicks of decreasing amplitude along the trace are the tubing collars, and the fluid level "kick" is on the right side.
To determine the depth to the fluid level, either the average acoustic velocity of pressure wave must be derived or the number of tubing joints above the fluid level must be counted and then related to the average length of tubing (feet/joint). Counting the tubing collars is the most common method, but two other possible methods exist for determining the acoustic velocity if, for example, the tubing collars don’t show up clearly (noisy well), or a fluid level shot is taken down the tubing (and there are no collars to count).
Directly after taking the Fluid Level Shot, a Casing Pressure Build-Up Test is performed which quantifies the instantaneous gas flow rate producing up the casing. With the depth to the Fluid Level and the instantaneous gas flow rate up the casing being known, the well's GFLAP (Gas Free Liquid Above Pump) is computed. When the well is Pumped Off and no liquid resides above the pump (assuming the pump is set below the perfs) that means the pressure drawdown on the formation—and thus the well's production—are Maximized. And Maximized Production is DynoMight!
If sufficient GFLAP resides above the pump and your downhole gas separator is properly designed, the Dynamometer should find the pump full of fluid each stroke (unless something is restricting the fluid inflow, like a plugged sand-screen). Fluid Level Surveys have widespread application to other forms of Artificial Lift (like ESP wells, Gas Lift, and Plunger Lift) and Fluid Level shots down the tubing can often come in handy when troubleshooting wells that don’t have fluid to surface.
To summarize, the main function of the Fluid Level Shot is to locate the depth to the top of the gaseous Liquid Level (Fluid Level Kick), quantify the amount of pumpable liquid above the pump (GFLAP), and determine the Bottom Hole Pressures.
Click the Acoustic Trace above for more details and example Fluid Level Survey reports.
A Dynamometer quantifies the loading on the rod string and how the pump is operating from stroke to stroke.
A dynamometer is attached to the top of the rod string and measures the changing load on the Polished Rod each stroke that results from the rods (pump plunger) carrying the fluid load on the upstroke and releasing the fluid load on the down-stroke. A plot of of the surface acquired Load vs Position data is known as the Surface Card (Ex: the "duck" looking card above).
The Wave Equation (which accounts for the elastic nature of the rod string in its dynamic motion) is applied to the Surface Card in order to mathematically filter the surface data to calculate what is happening at the downhole pump. A plot of the converted data is known as the downhole Pump Card and represents the load on the pump's plunger as the plunger moves up and down through each pump stroke (shown in the rectangular "panhandle" cards above). By observing the shape of the Pump Card during a single stroke—and also comparing successive pump strokes to see how the shape changes during the run cycle—the downhole operating conditions, producing efficiency, and pump performance can be evaluated.
The Pump Card above shows a well that had 2 full pump strokes then went to an incomplete fillage card (Fluid Pound) as the card starts to take on the panhandle shape. This panhandle shape is due to the fluid load not being released off the pump plunger at the start of the down-stroke (due to the well being pumped-off and there not being enough fluid to fill the pump chamber with liquid).
Important information gathered from a Dynamometer Survey include: what the liquid fillage of the pump is; how much of the surface stroke length actually contributes to actuating the downhole plunger (i.e. how much of the stroke is lost to rod stretch); if the well’s run timer is properly set; if any impact loads due to pump tagging or fluid-pound are occurring; how effectively the downhole gas separator is functioning; and, how worn the pump is (i.e. how much "fluid slippage" is occurring).
While the Fluid Level Gun allows for the quantification of how effectively the reservoir is being produced relative to its maximum potential, the Dynamometer quantifies how effectively the Rod Pumping System is lifting the fluids to surface. Although the two tools are evaluating different aspects of the downhole conditions, they are completely complimentary and synergistic in nature. The measurements acquired from each tool provide validation (or not) to the measurements of the other tool—which is essential for diagnosing and troubleshooting cantankerous wells.
For a more detailed description with example reports of Dyno Surveys—click the Dyno cards above.
I am not the cheapest, but I provide the best value. I am an engineer, so the data I acquire is accurate and my insights/application of how to best apply the FL/Dyno data to optimize your wells is where the true value comes from. I know all the POC's, can program/calibrate them and I can raise/drop rod strings as needed.
Shawn Dawsey @ 432.230.8700. Cheers!