Method of monitoring gas influx into a well bore when drilling an oil and gas well, and apparatus constructed in accordance with the method
A method of monitoring gas influx into a well bore when drilling an oil and gas well. A first step involves positioning a pressure sensor in a well bore at a lower end of a well casing string. A second step involves connecting the pressure sensor to a pressure reader and monitoring the pressure reader for pressure changes indicative of gas influx.
The present invention relates to a method of monitoring gas influx into a well bore when drilling an oil and gas well, and an apparatus constructed in accordance with the method.
BACKGROUND OF THE INVENTIONThe influx of gas into a well bore can cause a “blow out” condition. Every drilling rig is equipped with a Blow Out Preventer, which consists of hydraulic rams that can close the well bore if a “blow out” condition is detected. Some Blow Out Preventers have “shear” rams, which are capable of shearing the pipe off; so that the well bore above the cut pipe can be closed off completely. Gas influx is presently detected by closely monitoring changes in circulation of drilling fluids.
SUMMARY OF THE INVENTIONAccording to the present invention there is provided a method of monitoring gas influx into a well bore when drilling an oil and gas well. A first step involves positioning a pressure sensor in a well bore at a lower end of a well casing string. A second step involves connecting the pressure sensor to a pressure reader and monitoring the pressure reader for pressure changes indicative of gas influx.
BRIEF DESCRIPTION OF THE DRAWINGSThese and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to in any way limit the scope of the invention to the particular embodiment or embodiments shown, wherein:
The preferred method of monitoring gas influx into a well bore when drilling an oil and gas well will now be described with reference to
Referring now to
The apparatus to be used to monitor gas influx into well bore is shown in
In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the Claims.
Claims
1. A method of monitoring gas influx into a well bore when drilling an oil and gas well, comprising the steps of:
- positioning a pressure sensor in a well bore at a lower end of a well casing string; and
- connecting the pressure sensor to a pressure reader and monitoring the pressure reader for pressure changes indicative of gas influx.
2. The method as defined in claim 1, the pressure sensor being positioned in the well bore by incorporating the pressure sensor into a cavity in tubular members making up the lower end of the well casing string.
3. The method as defined in claim 2, the pressure sensor being positioned within a float collar at the lower end of the well casing string.
4. The method as defined in claim 3, a fluid communication port being provided through the float collar to the cavity to allow fluids in the well bore to communicate with the cavity in which the pressure sensor is positioned.
5. The method as defined in claim 4, the fluid communication port having a protective closure which closes the fluid communication during cementing, the protective closure being removed after cementing.
6. (canceled)
6. (canceled)
7. An apparatus for monitoring gas influx into a well bore, comprising:
- a tubular body having defining side walls with an interior surface and an exterior surface,
- a pressure sensor being positioned within a cavity formed in the side walls;
- a passage extending from the interior surface into the body to provide fluid communication with the cavity; and
- means for communicating pressure sensor readings from the pressure sensor to a pressure reader positioned on surface.
8. The apparatus as defined in claim 7, wherein the tubular body is a float collar.
Type: Application
Filed: Jun 13, 2006
Publication Date: Jan 4, 2007
Inventor: Javed Shah (Edmonton)
Application Number: 11/452,655
International Classification: E21B 47/00 (20060101);