Well Prototypes and Clones

Cloning means using a single specification for modeling multiple actors in the simulation. That is: once you have defined an entity, typically a well, you can later instruct PetroVR to use it as a prototype for creating a series of identical copies. Therefore, that well already defined in the reservoir will serve both as a model for the clones, and as a concrete well to be completed side by side with its clones.

The first and foremost advantage of cloning is that it allows you to avoid redundancy in your specifications: wells and other entities intended to be identical can thus be defined from a single place. Thus, by reducing the steps you need to define a number of identical actors, both the simulation and the navigation become faster.

Jobs involving the concept of cloning actually have as their primary object the completion, not the wellbore. It is the completion that will be replicated, with the wellbore accompanying it. Wells included in these jobs, therefore, are scheduled to be drilled if necessary and to be completed immediately afterwards; in this Respect, the jobs work similarly to a Well Drilling job with the option Complete wells automatically once drilled checked.

The Cloning Sequence Number

Every clone is named after its prototype plus an identification number or Cloning Sequence Number: <2>, <3>, etc. These numbers will be consecutive, even if the clones themselves have been created by means of different jobs at various times, and will characterize that clone throughout the project life.

Correspondence between Cloning Sequence Numbers

If two or more completions in the same wellbore are used as prototypes in cloning jobs, their clones will still share a wellbore, and will receive the same sequence number as other cloned completions in that wellbore. This is particularly important for the task of drilling those wellbores: drilling will obviously not be necessary if a completion with the same sequence number already exists.

During the simulation, it may happen that the clone of a recompletion gets scheduled to be performed before the clone of the primary completion. According to the rule stated above, the recompletion should not be able to drill its wellbore, so that it would not be performed until the primary completion finally has its wellbore drilled. Cloned wells, however, work differently than specification wells in that the first completion scheduled to be performed becomes the primary completion, no matter the status of their prototype completions in the specification well. In the example illustrated above, Well WO1 <4> and Well WO1 <5> actually work as primary completions; and in the case that Well WO1 <3> were scheduled to be performed before Well <3>, it would become the primary completion and scheduled to be drilled immediately.

Facility Cloning

As explained above, facilities can optionally be cloned along with wells in well cloning jobs. These jobs address first the drilling and completion of wells, and then adjust the cloning of facilities to manage the routing of fluids in one of two alternative ways: by making sure the facility is ready to operate only when the wells can start producing, or conversely to make the construction job finish the moment the wells start being drilled. These alternatives are intended to model whether the facility is a prerequisite for drilling wells or not; the former case will typically apply in on-shore projects, and the latter in off-shore platforms.

Cloning facilities represents a real challenge because PetroVR needs to anticipate as best it can the conditions under which the building of a facility clone should start. But the potential complexity of a model is such that it is not possible to anticipate the future before running the simulation. Therefore, in certain cases the timing of the clones will be suboptimal.

Facilities can also be cloned independently from well cloning jobs by enabling the Cloning Excess Policy in the Excess Policy Tab. This policy triggers the creation of clones every time the facility's capacity is about to be exceeded. Since it is not directly dependent on the cloning of wells but on general routing needs, it can be used to clone facilities that are not directly connected to a reservoir being developed by an Automatic Development job.

Facility clones are not included in other jobs that refer to their original facility (which may be Facility Production Rerouting, Facility Expansion and Facility Maintenance). Facility clones are abandoned when their prototypes are abandoned - see Abandonment.

Cloning jobs will clone facilities in order to accommodate cloned wells only - not prototypes. The purpose of this is to allow you to queue wells that must be connected to a facility with a maximum number of connected wells without triggering a facility cloning.

Injection Facilities are not cloned along with the injection wells connected to it. All clones of an injection well are connected to the original injection facility.

In some cases it is possible for facilities to be cloned even before the prototype facility is built. For example, if the model says that a facility should be cloned as soon as the wells have been drilled, clones will start to be built as soon as this condition is met, regardless of whether the construction job for the original facility has begun.

The number of facility clones required by an Automatic Development job is calculated at the start of the job, establishing a limit on how many facility clones can be built by the job. If Max Connected Wells is enabled so that the number of clones depends on the number of wells that can be connected, and is defined as a function of runtime variables, any change later than the start date of the Automatic Development job will not be taken into account.

Clones and Well Jobs

When a job that operates on an existing well ( ESP Installation, Gas Lift Installation, Well Production Rerouting, Well Decline Manipulation) is applied to a prototype, it will also affect both its existing clones and those drilled afterwards - not clones already abandoned.

Self-References in Cloned Wells and Facilities

When a well or a facility variable defined as a function contains a reference to another variable belonging to the same entity, the corresponding variables of the clones are automatically referred to the clone rather than to the prototype. Thus, in an expression like:the reference "Production Start" always points to the production start date of the clone, not the prototype well "Hermes".

Cloning Wells with Distributions

When cloning wells, it is important to notice that if a distribution is defined for a given input, this distribution will not affect clones differently, i.e., all replications will receive the same values within each MC iteration. Jobs that embody the concept of cloning model the behavior of a set of identical wells in a given scenario, and not variation within this set - for which the Duplicate command is best used. See further in Duplicating objects.

Kinds of Cloning Jobs

PetroVR uses the concept of cloning in several different jobs, with different aims.

Well & Facility Cloning is the most flexible one, well-oriented, to be used when creating a given number of clones regardless of the reservoir they belong to.

Automatic Development is specially useful in reservoir-oriented projects, where a reservoir's limits determine the scope of cloning. However, since reservoirs will admit only one Automatic Development job, modeling partial developments of a reservoir is best done using a W&F Cloning job.

Infill Drilling, on the other hand, makes use of cloning for cases where the reserves of a group of existing wells are affected by the coming into production of infill wells.