Methods for well control | oil engineering

in StemSocial2 months ago

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In this opportunity I want to bring to relevance the different methods to control an oil well, mainly in the drilling works. It is important to emphasize that these methods bring implicitly a procedural methodology very fed by some mathematical tools that are important for the moment of their control.

Introduction

Although there are several methods to control a well, the most used in the oil industry are

  • Driller's method.
  • Engineer's method.

Considering the diversity of control methods we can say that the principle of these methods are the same, that is to say the application of these methods maintain the pressure in the bottom of the well to the desired level, generally this pressure in the bottom is in the balance or a little above the balance.

In the wells in which an emergence is presented the most advisable thing is to control the pressures in the bottom of the well until the influence of the well comes out, to later pump a mud with a higher density that can control the formation pressure.

In conclusion the two mentioned methods fulfill the final objective to control the influx of the formation and to avoid the loss of circulation of the drilling mud, the only difference that we can find between these methods is that in the engineer's method there is a control in the pressures in the bottom of the hole, nevertheless in the driller's method there is no control of bottom pressures, since it is taken advantage of the same circulation of the fluid to take out the influx of gas and oil from the bottom to the surface.

Driller's method of controlling the well in the event of a formation fluid invasion

This method of well control employs a technique in which the drilling fluid is circulated to draw the inflow (gas and oil) out of the well. In this method it is important that we understand what is the fundamental technique to be used and the ideas used in the application of it, since there are other methods of well control that use many of its principles.

The disadvantages of this method cannot be ignored, the Driller's method can cause high pressures in the casing compared to other methods, the other thing to take into consideration is that the technique of the Driller's method requires more time to drown and control the well.

Where is it advisable to apply the hole punch method?

1] The drill method is ideal to be applied during maneuvers, since once you return to the bottom of the well, the column of fluid in the annular space circulates and removes the influence.

2] It is also ideal for application at times when no chemical thickener is available to increase the density of the drilling mud.

3] The Driller's Method is suitable for use in drilling operations, well rehabilitation where equipment and personnel are limited.

4] It is not advisable to apply the Driller's Method in those wells where a loss of circulation is anticipated or expected, since the pressures that are handled at the bottom of the well with this method are very high and may fracture the formation, thus occurring a loss of circulation of drilling fluid.

In conclusion we can see that the driller's method is very applicable when resources are lacking, and apart from that it is very applicable where a very fast and on-the-spot response to control is required.

How is the puncher method applied?

With the Driller's Method we are able to remove the inflow from the well in two stages, these two stages can be summarized as follows: a first circulation of drilling fluid where we remove the inflow from the well. Then if we realize that the existing drilling fluid in the well is below the formation pressures, we proceed to replace the existing drilling fluid with a new fluid of higher density until we achieve control of the well.

The method is summarized as follows:

1] The well is closed, using either soft close or hard close techniques, depending on the operation being performed at the time.

2] The well closing pressures in the drill pipe (SIDPP) and casing closing pressures (SICP), already stabilized, are recorded.

3] Circulate and remove the invading fluid (surge) from the well. To circulate the well with the existing fluid in the well, it is necessary to follow some valve opening and closing guidelines, where the choke line will be aligned and the HCR valve will be opened, for this I invite to observe and listen to the video at the end of the explanation of the methods.

4] When the well is completed and the influence is removed, the well is closed for the second time, always checking that the closing pressures do not exceed the maximum admissible surface pressure (MAASP). The closure of the well for the second time must be done applying the same methodology of the first closure.

5] If it is determined that the existing drilling fluid in the well generates a lower pressure than the formation fluids, then the density of the existing fluid is increased, or a fluid with a higher density is prepared and replaced by the existing one in the well.

6] The well is run a second time, with the intention of removing any new inflow that may have remained in the well. This second circulation is done either with the same fluid, this in case the mud has enough density to generate a higher pressure than the formation fluids, or it can be done with a heavier mud that has been prepared for the second circulation of the mud.

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Waiting and Weighing Method (Engineer's Method)

Like the perforator method, this method has its advantages and disadvantages, its use as well as the perforator method depends on the conditions at the time. The engineer's method kills the upsurge in a shorter time compared to other methods, while keeping the well and surface pressure ranges at optimum levels for control.

All this makes this method the most recommendable one to apply at the moment of controlling a well before an emergence, however if you do not have all the available resources it is not very recommendable to apply it, because it is necessary good mixing facilities for the preparation of the drilling fluid, complete crews and an additional help for the supervision in its application.

Practically the control of the well by means of the application of this method is made in a single cycle, that is the difference marked in comparison to the method of the perforator that its control is given in two phases. In this method, once the emergence is detected, the well is closed by means of the already known methods, the closing pressures already stabilized in both drill pipe and casing are recorded, also the volume of gains produced by the emergence in the travel tank is noted. Before the circulation of the mud begins, its density is increased, hence the name "wait and see". A single circulation is then carried out with the weighed sludge, always maintaining the correct density and pressures, during the well control.

The reality in field practice is that controlling a well by performing a single circulation is not very convenient, since the displacement that occurs between the space between pipe and hole (annular space) is inefficient in many cases, so in any of the methods to be used it is recommended to perform two circulations of the drilling fluid. The application of the Engineer's method is presented below in a systematic and summarized way:

1] The well is closed, using either soft close or hard close techniques, depending on the operation being performed at the time.

2] The well closing pressures in the drill pipe (SIDPP) and casing closing pressures (SICP), already stabilized, are recorded.

3] The fluid density is increased until the calculated density of the control fluid is reached.

4] When the mud in the active tanks is ready, the fluid is circulated.

5] The drilling fluid is pumped following a table where for each value of circulation pressure a specific value of drilling fluid volume is pumped for well control until the final circulation pressure value is reached.

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Conclusion and contributions within petroleum engineering

It is the responsibility of all involved in well control to maintain proper circulation pressure as the control sludge is pumped from the surface to the wick, and from the wick to the surface. Therefore, adjustments in pressure should be made as needed.

During well control it is necessary that there is effective communication between the personnel involved for closure and subsequent control, after each member of the work team has received instructions about their work responsibilities they can begin with well control.

Once control has begun, information collected after closure, such as shut-in pressures and well control math, can be verified and, if deviations exist, corrected. All of these changes must be communicated to all members of the well control team, keeping in mind that well control is a team effort.

It is necessary to apply the technique for the control of the well that best fits the existing conditions for the moment, each well is unique, so plans must be made to control the well based on the conditions of each well.

Each method that attempts to be applied in well control must be studied carefully, since as explained in this article the driller's method and the engineer's method are proven methods for controlling wells under the conditions for which they apply. Science and engineering studies applied to these methods, apart from the field application experience have determined that certainly these methods have their advantages and disadvantages, variables such as pressure, mud volume, mud pump capacity, type of upwelling, location of the camp, affect the selection of the appropriate method to control the well.

With all of the above, I can tell you that apart from the mechanisms and implements that we have in our favor, the most important thing that we must have in the control method to be selected is experience and common sense to solve the problems that arise in the control of the well.

Reference consulted and recommended

METHODS OF WELL CONTROL- DRILLER'S METHOD

Well control. Petrowiki

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