Example 1 Here is a short guide on executing the Step-Down Analysis examples we sent out. Remember, you do not need to get exactly the same numbers. What is important in these exercises is to determine if the total entry fiction is a problem, if so what remedial action is needed to alleviate entry friction; how the friction drop is related to the changing rates in the high and low ends; and determine which of the friction components is predominating ie. (Beta factor). Select correct input file on F3 Screen, “Friction #1.INP”

Select correct database file on F4 screen, “Friction#1.dbs”

Select correct data channels on Shift + F6 screen:

Copy Design to Actual schedule on F6

Set Staging by clicking on, “Set Staging from Measured Data” on F6 screen and run simulator.

Create a plot with Measured Bottom Hole Pressure and Bottom Hole Slurry Rate

Click on cursor editing

Set the cursor before the first step, click in “begin” button then set the cursor at the end of the step, click on “end” button. Click on “manually step down entry” and repeat the process with the following steps.

(Last Flag should be on the ISIP)

Click “Step down data” and close plot. Then open F8 screen for results

If the ISIP is not available to pick, we can create two tangent lines to read that point. (Place cursor on pressure line and right click) One line tangent to the pressure decline and the other one horizontal to the point where intersect with the first rise of water hammer. Place the mouse in the intersection; right click to read the pressure. Calculate the delta pressure for the last step using the pressure before the step and the ISIP. Then you can manually change that value in the F8 screen. Analyze Step-down analysis screen.

What perf Friction is dominating? What is the estimated Perfs open? Is your beta factor in recommend range? Is your last flag set on your ISIP and have a bottom slurry rate of zero? Does your BHTP step-down trend make sense? What solution(s) exist to the entry friction problems if any? These are some questions you should ask yourself when analyzing the step-down data.

Example 2.

Immediately one can see that the BTHP is increasing as rates decreases. This is due to an overestimation of friction by FracPro. The F5 screen on the injection fluid should reveal the problem. A friction multiplier of 1 should be fine on WG18_2_20 fluid. The step-down flags do not net very much manipulation. Your beta should end up being around 1.

Hint: In this case you can put the last flag very close to the middle point of the first raise of the first water hammer. There will be instances where it will not possible, in those cases, including a tangent line will give you an accurate ISIP. Calculate the delta pressure for the last step using the pressure before the step and the ISIP. Then you can manually change that value in the F8 screen.

This is the end of the example 2. Please read the discussion of the importance of selecting a right ISIP value.

Selecting the right ISIP If the ISIP is designate too High on the “Meas’d BHTP Pressure graph, the ΔP will be smaller than the real value, and it will result in having High Perforation Friction. (, thus giving inaccurate results.)

Making the ISIP too Low on the “Meas’d BTMH Pressure” graph, theΔP will be larger than than the real value, and it will result on having High Near Wellbore Friction. (, thus giving inaccurate results.)

Thus, by creating a tangent line, is ensure that the ISIP is in the proper location giving us the correct ΔP. Gathering these results and inputting them manually back into FracPro ensures that the modeled results are accurate. Remember this difference in pressure is the entry friction pressure.

Example 3. The channels on this example were not renamed when the file was converted over to an rtd file. When this occurs it is good practice to revise the channel assignment in FracPro. This is simply done by clicking the “View Measured Data” on the shift+F6 screen. Taking a look at the plot it looks like we have the channels assigned correctly.

View measured data Plot

The BHTP increases on the last step-down. Does this sound familiar? Yes you might want to check the friction in FracPro.

Complete the Step-Down Test

Look if your beta factor is out of the recommended range (0.5-2).

If the Beta factor and all frictions are zero, the last flag was place when rate was still going. Make sure the last rate of the test is zero.

If the Beta factor is greater than 2, something still wrong with the test.

Remember FracPro account for what fluids are being pumped in from start of job to finish. A full string of KCL water is being pumped in before the WFH_20 hits the formation. Adjusting the friction not only in the WFH_20 but as well in the 2%KCL will remedy the problem. Remember you will probably not get the exact numbers as I, but your results should show the same entry friction problem if one exist. On this example placement of the last step-down flag is essential. Due to the rate spike at the end of the treatment, ISIP should be found by a tangent line and adjusted in the result table.

Example 5

Pretty straight forward. How do you think we could remedy this problem of entry friction? Example 6

0 perfs open?!!! Can that be possible? Of course not, FracPro step-down analysis is based on pressure drop and rate changes in the different step-downs performed. FracPro is able to calculate the entry friction even if no perfs exist in its input parameters. Take a look at the Wellbore configuration screen F7, and you will see that the “perf intervals” tab is missing the number of actual perfs run in this job.