GNVP: transcript, direct and indirect signs

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The gas and oil industry is one of the most serious and responsible activities. State of emergency in this area, in fact, should be discussed only in theory. Against this background, it is important for both ordinary workers and managers, and those who are educated to be employed in the industry related to drilling wells, to know the decoding of the GNP, as well as the signs, causes, and ways to eliminate this phenomenon. Let's start with the general characteristics.

GNVP transcript

The letter combination GNVP means gas, oil and water shows. This is the simultaneous penetration of gas and oil fluid both into the well through the strings and into the outer annulus.

Knowing the decoding of the gas oilfield, we have a rather serious problem that may arise during drilling. It requires immediate elimination. Most often, gas, oil and water shows are detected at high reservoir pressure due to excessive bottomhole deepening, as well as due to incorrect actions of drillers or repairmen.

Causes of the phenomenon

The approval of the GNVP (decoding - gas-oil-water shows) in production is very undesirable. Herethe main causes of this problem:

• Initially incorrect work planning. This led to erroneous actions when creating the pressure of the working solution during the overhaul. External pressure pushed through the connecting seam of the columns, which led to the GOGVP.
• The reason may be inside the well - this is the absorption of fluid.
• During downtime, the density of the working fluid decreased due to the penetration of gas or water through the walls.
• Trips were planned incorrectly - as a result, they led to a decrease in the liquid level in the column.
• The correct time interval has not been observed between work cycles. One of the main reasons was that there was no flushing for 1.5 days.
• Violated a number of rules for work in the mine - for the operation, development, and elimination of emergencies.
• Reservoirs are being developed, characterized by a high content of water and gases dissolved in it.
• Development of fluid loss processes in the wellbore.

Signs of the STRP

Signs of detection of gas-oil-water manifestations are usually divided into two categories:

• Early. Characteristic when oil fluid enters the wellbore. Within themselves, they are subdivided into direct and indirect signs of GNVP.
• Later. Characteristic for the moment when the formation fluid is already on the surface.

Let's look at the categories in more detail.

Early signs: direct

So, let's start with the direct signs of the STG:

• Volume increase(meaning fluid has already started flowing into the well).
• Increasing the speed (increase in flow rate) of the flushing fluid outlets when the pumps flow remains unchanged.
• Decrease in the amount of added liquid when lifting the pipe string against the calculated volume.
• Discrepancy between the volume indicated above and the volume of lifted instruments.
• Increase in the flushing fluid that enters the receiving tank when the pipes are lowered, compared to the calculated indicators.
• Flushing liquid continues to flow through the trough system when circulation stops.

Early signs: indirect

So, indirect signs of the STG:

• The mechanical drilling speed has increased. This indicates the occurrence of a depression, a decrease in back pressure on the formation, or an entry into easily drillable rocks.
• The pressure on the pumps (riser) has dropped. It may indicate the release of a large volume of light fluid into the annulus or the formation of a siphon. It is also a sign of a violation of the tightness of the column, a malfunction in the operation of the pumps.
• The weight of the drill string has increased. It may be a sign of a decrease in the density of the drilling fluid due to the introduction of formation fluid into the well. And also this is a manifestation of reducing the friction of the string against the walls of the well.

Indirect signs are paid attention only in the presence of direct ones, because they only speak of a possible gas oil spill among the causes of other problems. When they (indirect signs) appear, control over the well is enhanced. This is necessary to identifyalready direct signs of GNVP.

Late signs

And now the late signs of a problem:

• At the circulation outlet, the density of the washing liquid drops.
• It is observed boiling, the appearance of a characteristic smell.
• Gas logging station shows an increase in gas content.
• During heat exchange with the formation at the outlet, an increase in the temperature of the drilling fluid is observed.

Actions when a problem is detected

Immediately after identifying the problem, the staff starts to eliminate it. These are two ways:

1. Cessation of oil production from the well where oil and gas oil was found.
2. If there is intensive development of the reservoir, then work is also suspended on adjacent wells to avoid a widespread problem.

First of all, the watch seals the mouth, channel and wellbore, be sure to inform the management about what happened. As soon as the signs of a gas-oil-water show are established, a special team gets down to business - workers who have undergone specialized training and have the appropriate qualifications.

Liquidation is carried out with the help of special equipment: pipes are lowered under high pressure conditions. In order to stop the processes of gas-oil-water treatment, an optimal level of equalizing pressure is created in the wellbore. It can be equal to the reservoir value or exceed it.

During the descent of the equipment in the conditions of the oil and gas pipeline, there may be a gushing. Then the brigade proceeds to jam it,based on emergency orders. Additionally, representatives of the technical supervision organization are involved.

When gas-oil drilling is performed, the well is blocked with a barite plug. It creates an impermeable screen in the seams and allows a cement bridge to be placed on top. If a gas-oil-water show is opened during the operation of two pumps, then their operation is provided either from one tank or from two, but with locking devices between them.

Methods of elimination of gas oil and gas pipelines

Once the true cause of GNVP is established, it is necessary to choose the one most effective way to eliminate it. There are four in total.

Well killing in two stages. The most important thing here is a clear division of the work stages into washing out the oil fluid with the same solution that was at the time of the discovery of the cause of the oil-well-water treatment, and the simultaneous preparation of a new solution having the required density for killing. The first stage is well plugging. The second is the replacement of the working fluid.

Step mute. It is effective when the pressure in the column before the throttle increases relative to the value of the maximum allowable for it (the column) or hydraulic fracturing of the shoe level. First, the throttle is opened slightly to reduce the pressure in the column.

Because of this, a new flow of water and gas will be observed at depth. Since the peak of the resulting pressure is short-term, the next time the throttle is slightly opened, while flushing the well. The actions are repeated until the complete disappearance of the signs of GNVP, the normalization of peak pressure indicators.

Waiting for weighting. As soon as it is discoveredgas, oil and water show, the personnel stops oil production, shuts off the well. After that, a solution of the required density is prepared. It is necessary to maintain pressure in the wellbore, which is similar to the formation pressure, in order to stop the oil-water treatment and further ascent of the oil fluid to the surface.

2-stage extended muting. After the detection of GNWP, the fluid is washed out with the same solution. Then its (solution) density changes to the required one. The method is mainly used in the absence of suitable containers for preparing the required volume of working fluid. The method got its name due to the fact that the process of washing out fluids with it is somewhat more extended in time than with conventional two-stage killing.

Education and training of personnel

According to the Safety Rules in the oil and gas industry (clause 97), we can establish that once every two years, knowledge is tested in the section "Well control. Management of work at (the reader knows the decoding) GNVP". The certificate is given for three years.

The above applies to employees who carry out both direct work and manage processes by:

• drilling and well development;
• their repair and restoration;
• performing-explosive and geophysical works on these objects.

The sooner the oil and gas pipelines are detected, the more chances there are to prevent the aggravation of the problem - significant downtime of oil production, whichleads to large financial losses. To prevent the development of gas, oil and water shows, it is necessary to pay due attention to external sensors of volume, density and pressure of the working fluid.