Getting results is made easy in Cerberus by the Question & Answer Wizard.  The main calculation tasks are presented as questions, and you simply click on the one you are interested in. The symbols on the left indicate the type of result or calculation you will see, for example a numerical result, a graph or a calculation wizard. The questions are divided into four logical sections, as shown below. [Note that some of the questions are different for jointed pipe and wireline, click on the links to see those versions]

• Selecting the CT string and BHA

• Getting into and out of the well

• Performing the job at depth

• Other calculations

What is the optimum string design for this job? - the String Design Wizard is an advanced feature which turns the usual modeling task on its head. Instead of you specifying the string design and then running the model to see if it can do the job, the Wizard asks you to define the job and then designs the best string to do it. The Wizard takes into account factors like road weight and reel capacity as well as mechanical properties. Once designed, the Wizard can submit a request for a quote from the major manufacturers.

Which existing strings are candidates for this job? - the String Select Wizard scans the strings in your inventory, and also (via the internet) those available at the manufacturers and other bases in your organization, to find the strings which match your requirements.

What size BHA will be able to navigate the bends in the well? - the Toolfit Wizard will tell you what tool dimensions (length and diameter) will fit in a given well size and dogleg severity. If it is necessary to bend the toolstring to get around the corner, the Wizard will tell you how much force is needed.

What is the optimum release setting for a mechanical disconnect? - the Weak Point Wizard helps you chose the optimum disconnect to ensure you can achieve maximum overpull if you get stuck, yet still break the disconnect if you need to without risk of breaking the pipe first. Incorrect selection of disconnect for a job in a deviated well can be a major problem, because many engineers tend to underestimate the effect of the additional drag caused by the bends in the well.

GETTING INTO AND OUT OF THE WELL

Can I reach the target depth and return to surface safely without CT lockup or yield? - can you reach the target depth without the tubing locking up, and then return to surface without breaking it. This gives you a quick answer to one of the most important questions. Example

Plot a graph of surface weight against depth - this essential graph shows you what the surface weight readings should be while running into and out of the well. Print this graph for comparison with actual measurements at the wellsite. The same graph displays the disconnect (if any) and pipe breaking strength limits, and hence what your available overpull is at each depth if you should get stuck. [Note: this is especially useful when run in real-time with the Orion data acquisition system] Example

Plot a graph of maximum set-down force (WOB) against depth - how much force can you set down at the end of the toolstring (by slacking off at surface) for each depth. This is extremely important for planning operations requiring mechanical force to be applied downhole, for example when moving a sleeve, fishing or drilling. Example

Plot a graph of maximum pick-up force against depth - this very important graph shows you how much pull you can apply at the end of the toolstring for each depth before you break the pipe. Example

Plot a graph of stretch against depth - the program can calculate what the stretch is at each depth, and hence the “true” depth. Some customers use this feature for depth correction, particularly when running depth-critical applications, for example perforating. Example

If the production tubing is buckled, will I be able to pull out? - buckled, or corkscrewed, production tubing can present a major problem. Going into such tubing may pose no difficulty as the tools drop under gravity, but as soon as you reverse direction and try to come out, the CT pulls against the helical tubing and the greatly increased drag may make it impossible to pull out without exceeding the pipe breaking strength. This Wizard enables you to estimate the degree of buckling, and then superimpose this profile on the well geometry when performing the regular calculations. This feature is unique to Cerberus. Example

If I need a tractor to reach TD, what is the maximum pull required? - this graph of how much tractor pull is required at each depth to overcome drag is useful for two reasons. First, you can ensure that the tractor under consideration is capable of performing the job, and secondly you can optimize the tractor pull at each depth to avoid running it unnecessarily at full power all the time.

PERFORMING THE JOB AT DEPTH

 How does the set-down force (WOB) vary with surface weight? - the program calculates the maximum set down force, and the corresponding surface weight.

How much pull can I apply at this depth? - the program calculates the maximum pull, and the corresponding surface weight.

What will the depth counter read, accounting for stretch? - the program calculates the stretch at each depth, which can used to correct your measured depth at the wellsite.

What are the forces acting at this depth? - this feature gives a detailed break-down of the component forces which are contributing to the net situation. This can be useful to understand if difficulty reaching depth is due to frictional forces or fluid effects (choking the well or circulating out to a different fluid may help).

What are the forces acting at this depth? – a detailed breakdown of the component forces (weight, buoyancy, drag, etc) acting on the pipe.

Plot a graph of CT tension vs depth - this is one of a family of graphs which display the conditions along the pipe with the toolstring fixed at a particular depth. The other graphs include hydrostatic pressure and wall contact force.

View a 3D animation of CT tension vs depth - this diagram shows the status (tension/compression /buckling/yield) of the pipe relative to the well geometry. You can animate the diagram in order to view how the status changes with depth. This is particularly useful when demonstrating a difficult point to a client.

OTHER CALCULATIONS

Use the Report Wizard to generate a full analysis and print a report - this Wizard allows you to perform all the key calculations and print a summary in one step, rather than do each one separately. This task is usually done last, after a detailed analysis has been completed manually.

Run a sensitivity analysis of key parameters - this task is extremely important, in order to assess whether the job is marginal or straightforward. Running the project for only one set of input parameters runs the risk that slightly different conditions encountered during the job may produce a different result. The user should test the robustness of the results by trying a range of parameters. The Analysis Wizard automates this task.Example

The CT is stuck. Perform a pull test and estimate the stuck depth - the Stuck Point Wizard allows you to perform a pull test to determine where the pipe is stuck downhole. This calculation is relatively simple in a vertical well, but in deviated conditions only this program can account for all the downhole forces when answering this question.Example

If the well continued on the same trajectory, how much further could I go? - results may indicate that you can do the required job at the current depth, but if the well were to be extended a little further would this change matters? This is particularly useful for operators who are considering re-entry and well deepenings. Also, this result is a qualitative indicator of the difficulty of the present job - if a hypothetically deeper well can be entered successfully, the current well will most likely pose few problems.Example

What is the risk of differential sticking? - this Wizard allows you to specify downhole conditions which can potentially lead to differential sticking, and then estimate the effect of this sticking on the surface weight and the ability to pull hard enough to get free should it occur.Example

Find the friction coefficients which give the best match to observed data - this Wizard automates the task of finding what the friction coefficients should be to match measured data to model predictions. Previously, this involved a trial-and-error approach of manually changing the friction coefficients and generating the surface weight graph, noting the offset and going through the process again with slightly modified coefficients until a match is obtained.Example