Patent FR-2783558-A1 (FR)
Title: Method for controlling gushing-type liquid and gaseous hydrocarbons production well involves controlling variable-aperture outlet choke in start up step where production is initiated and ramped up and then in production phase
Inventor: LEMETAYER PIERRE
IPC: E21B43/12
Filed: 1998-09-21
Abstract: The method provides a well with a production column (2) fitted with a variable-aperture outlet choke (9) and involves a start up phase which comprises a step of initiating the production of hydrocarbons and a step of ramping up to production speed. This is followed by a production phase during which the outlet choke is operated so as to maintain the stability of the hydrocarbon flow rate. The method includes the step of initiating hydrocarbons production which comprises gradually opening up the control means, that is fitted to the outlet pipe of the production column to control the flow rate, so as to achieve a predetermined minimum produced-hydrocarbons flow rate and then comparing the flow rate with a predetermined threshold. If the flow rate exceeds the threshold then the opening of the control means is suspended for the duration that the threshold is suspended. A step of ramping up to the production speed is then carried out which involves comparing the produced-hydrocarbons flow rate with a predetermined threshold T1, and if the flow rate exceeds the threshold continuously for a predetermined period of time D1 the aperture of the control means is increased to a predetermined value, while if the flow rate does not exceed the threshold then the comparison is repeated. A predetermined period of time is allowed to pass to allow the minimum hydrocarbons flow rate to become established after which the produced-hydrocarbons flow rate is compared with a second threshold T2, which is higher than T1, and the pressure upstream of the control means is compared to a predetermined threshold P1. If the flow rate and the pressure simultaneously exceed both of the thresholds continuously for the length of time D1, then the start up phase is finished and if they do not then the comparison is repeated. Preferred Features: The method additionally includes the steps of calculating the derivative with respect to time of the pressure upstream of the means for controlling the hydrocarbons flow rate and comparing the derivative with a predetermined negative and positive thresholds and if the derivative is above or below the positive or negative threshold, respectively, then the opening of the control means is suspended. The start-up phase additionally consists of calculating a well demand criterion which is compared with a predetermined threshold and, if the criterion exceeds the threshold, suspending the opening of the control means. The start up phase is followed by a production phase which involves defining a production indicator that is compared with two predetermined thresholds S1 and S2, with S2 being higher than S1. If the indicator is below S1 and the aperture of the control means is below a predetermined threshold then the aperture opening is increased by a predetermined amount while if the indicator is above S2 and the aperture of the control means is above a predetermined threshold then the aperture is reduced by a predetermined amount. The comparison is repeated and the produced-hydrocarbons flow rate is compared with a predetermined threshold and, if the flow rate is below the threshold then the control means is closed for a predetermined length of time and the start up phase is resumed. The production phase may involve calculating two product indicators Qa and Qb which are compared to two pairs of predetermined thresholds Sa1, Sa2 and Sb1,Sb2, with Sa2 and Sb2 being higher than Sa1 and Sb1, respectively. If Qa is below Sa1, Qb is below Sb2 and if the aperture of the control means is below a predetermined threshold then the aperture is increased by a predetermined amount while if Qa and Qb are above Sa2 and Sb2, respectively, and if the aperture of the control means is above a predetermined threshold then the aperture is reduced by a predetermined amount, with these comparisons being repeated. The control means is shut for a predetermined period of time and the start up phase resumed if Q1 is found to be below S1 or Q2 is found to be above S2. If the produced hydrocarbons contain water then at least one of the production indicators is the flow rate of the hydrocarbons, one of the flow rates is the flow rate of the hydrocarbons without water and one of the indicators is the water flow rate. At least one production indicator is the flow rate of produced gaseous hydrocarbons. The production phase additionally consists of calculating a well demand criterion and comparing this criterion with a predetermined threshold, with the aperture of the control means being reduced by a predetermined amount if the criterion exceeds the threshold. The demand criterion is calculated from a physical parameter measured on the well and the means for controlling the produced-hydrocarbons flow rate comprises an outlet choke on the outlet pipe. With the production column extended at its lower part by at least one hydrocarbons collection drain, the means for controlling the produced hydrocarbons flow rate additionally comprises at least one automatic bottom valve arranged on the drain. The flow rate is measured either by a flow meter on the outlet pipe, estimated from a measurement of the temperature of the produced hydrocarbons in the outlet pipe or estimated from the pressure difference across the outlet choke.