Wells – Processes – With indicating – testing – measuring or locating
Reexamination Certificate
1999-09-17
2001-09-04
Neuder, William (Department: 3672)
Wells
Processes
With indicating, testing, measuring or locating
C166S053000, C166S369000
Reexamination Certificate
active
06283207
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a method for controlling a liquid and gaseous hydrocarbons production well of the gushing type which feeds a downstream treatment unit.
2. State of the Prior Art
A known process for controlling the production flow rate of an oil well of the gushing type which comprises a hydrocarbons production column connecting the bottom of the well to a wellhead, connected by a pipe through a variable-aperture outlet choke to a downstream unit for treating the produced hydrocarbons, consists in positioning the outlet choke to set value so as to obtain a given produced-hydrocarbons flow rate.
This process does not allow effective control over the production of the hydrocarbons when plugs of gas form when the well starts production, as a result of the opening of the outlet choke, or when alternating plugs of gaseous and of liquid hydrocarbons occur, which plugs may be formed particularly in wells which have long drains with shallow, negative and varying gradients.
These plugs disrupt the production of hydrocarbons and this is manifested in an irregular supply to the downstream treatment units, such as liquid/gas separation units, or units for recompressing and processing the gas.
This irregular supply to the downstream treatment units has the following consequences:
it reduces the amount of gas that can be recompressed to be reinjected into the well or for sale,
it increases the wear on the equipment of these units, and
it increases the risks of tripping, which is manifested in a reduction in production.
Another consequence of these disturbances is an accentuation of the wear on the hole layer connection, particularly in wells sunk into unconsolidated reservoirs, and this leads to the ingress of sand which requires the installation of expensive sand-control equipment which may reduce the production capacity of the well or lead to frequent and expensive restoration of damaged wells.
Something else which this method is unable to provide is control over the initiation of a preferred flow of gas or water towards the bottom of the well from a zone of the reservoir which has been invaded by hydrocarbons in the gaseous form or by water.
Nor is it able to effectively compensate for the disruptions which result from the random behaviour of the reservoir, or for failure of the production column equipment.
The present invention is intended precisely to overcome these drawbacks, and to this end it provides a method for controlling a liquid and gaseous hydrocarbons production well of the gushing type, the well comprising at least one production column extended at its upper part by an outlet pipe for the produced hydrocarbons and fitted with variable-aperture means of controlling the hydrocarbons flow rate, the method being characterized in that it comprises a start-up phase which consists in performing the following sequence of steps:
a step of initiating hydrocarbons production which consists:
in gradually opening the control means to a predetermined value so as to achieve a predetermined minimum produced-hydrocarbons flow rate,
in comparing the hydrocarbons flow rate with a predetermined threshold and if the said flow rate exceeds the said threshold, in suspending the opening of the control means for the duration that the threshold is exceeded,
a step of ramping up to production speed which consists in performing the following operations:
comparing the produced-hydrocarbons flow rate with a predetermined threshold T
1
and if the said flow rate exceeds the said threshold continuously for a predetermined length of time D
1
, in increasing the aperture of the control means to a predetermined value, otherwise repeating the comparison,
waiting for a predetermined length of time to allow the minimum hydrocarbons flow rate to become established,
comparing the produced-hydrocarbons flow rate with a threshold T
2
higher than T
1
and comparing the pressure upstream of the control means with a predetermined threshold P
1
and if the said flow rate and the said pressure simultaneously exceed the said thresholds continuously for the length of time D
1
, in finishing the start-up phase, otherwise repeating the comparison.
According to another feature, the method of the invention additionally consists in periodically performing the following operations:
calculating the derivative with respect to time of the pressure upstream of the means for controlling the produced-hydrocarbons flow rate,
comparing this derivative with a predetermined negative threshold and with a predetermined positive threshold and if the derivative of the pressure is below the negative threshold or if the said derivative is above the positive threshold, in suspending the opening of the means for controlling the produced-hydrocarbons flow rate.
According to another feature of the invention, the start-up phase additionally consists in performing the following operations:
calculating a well demand criterion,
comparing this criterion with a predetermined threshold,
if the criterion exceeds this threshold, suspending the opening of the means for controlling the produced-hydrocarbons flow rate.
According to another feature of the invention, the start-up phase is followed by a production phase which consists in performing the following operations:
defining a production indicator,
comparing the production indicator with two predetermined thresholds S
1
, S
2
, S
2
being higher than S
1
, and:
a) if the production indicator is below S
1
, and if the aperture of the means for controlling the produced-hydrocarbons flow rate is below a predetermined threshold, in increasing the aperture of the said control means by a predetermined amount,
b) if the production indicator is above S
2
, and if the aperture of the means for controlling the produced-hydrocarbons flow rate is above a predetermined threshold, in reducing the aperture of the said control means by a predetermined amount,
c) in repeating the previous comparison,
comparing the produced-hydrocarbons flow rate with a predetermined threshold and if the said flow rate is below the said threshold, in closing the produced-hydrocarbons control means for a predetermined length of time and in resuming the start-up phase.
According to another feature of the invention, the start-up phase is followed by a production phase which consists in performing the following operations:
defining two production indicators Qa and Qb,
comparing these two indicators Qa and Qb with, respectively, two pairs of predetermined thresholds Sa
1
, Sa
2
and Sb
1
, Sb
2
, Sa
2
being higher than Sa
1
and Sb
2
being higher than Sb
1
:
a) if Qa is below Sa
1
and if Qb is below Sb
1
and if the aperture of the means for controlling the produced-hydrocarbons flow rate is below a predetermined threshold, in increasing the aperture of the said control means by a predetermined amount
b) if Qa is above Sa
2
and if Qb is above Sb
2
and if the aperture of the means for controlling the produced-hydrocarbons flow rate is above a predetermined threshold, in reducing the aperture of the said control means by a predetermined amount,
c) in repeating the previous comparison,
comparing Q
1
and Q
2
with, respectively, two predetermined thresholds S
1
and S
2
and if Q
1
is below S
1
or if Q
2
is above S
2
, in closing the means for controlling the produced-hydrocarbons flow rate for a predetermined length of time and in resuming the start-up phase.
According to another feature of the invention, with the produced liquid hydrocarbons containing water, at least one production indicator is the flow rate of the said hydrocarbons.
According to another feature of the invention, with the produced liquid hydrocarbons containing water, at least one production indicator is the flow rate of liquid hydrocarbons without water.
According to another feature of the invention, with the produced liquid hydrocarbons containing water, at least one production indicator is the water flow rate.
According to another feature of the invention, at least one production indicator is the flow rate of produced
Blank Rome Comisky & McCauley LLP
Elf Exploration Production
Neuder William
LandOfFree
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