Magnetic ranging while drilling using an electric dipole source and a magnetic field sensor

Abstract

A system and methods for drilling a well in a field having an existing well are provided. Specifically a method of drilling a new well in a field having an existing well includes drilling the new well using a bottom hole assembly (BHA) having a drill collar divided by an insulated gap, generating a current on the drill collar of the BHA while drilling the new well, and measuring from the existing well a magnetic field caused by the current on the drill collar of the BHA. Using measurements of the magnetic field, a relative position of the new well to the existing well may be determined.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a divisional application of U.S. patent application Ser. No. 12 / 105,698 filed Apr. 18, 2008, now U.S. Pat. No. 8,596,382 issued Dec. 3, 2013, which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates generally to well drilling operations and, more particularly, to well drilling operations using magnetic field measurements from an electric dipole to ascertain the relative location of a new well to an existing well.[0003]Heavy oil may be too viscous in its natural state to be produced from a conventional well. To produce heavy oil, a variety of techniques may be employed, including, for example, Steam Assisted Gravity Drainage (SAGD), Cross Well Steam Assisted Gravity Drainage (X-SAGD), or Toe to Heel Air Injection (THAI). While SAGD wells generally involve two parallel horizontal wells, X-SAGD and THAI wells generally involve two or more wells located perpend...

AI Technical Summary

Benefits of technology

The invention is about a method for drilling a new well in a field that already has an existing well. The method involves using a special tool called a bottom hole assembly (BHA) with a drill collar divided by an insulated gap. The BHA is placed in the existing well and an electric current is generated on the drill collar. The resulting magnetic field caused by the current is measured from the existing well. This measurement is used to determine the relative position of the new well to the existing well. The technical effect of this invention is to provide a more accurate way of drilling new wells in an existing field, which can save time and money.

Problems solved by technology

Heavy oil may be too viscous in its natural state to be produced from a conventional well.

Using many conventional techniques, the point of closest approach between the two wells may be difficult to locate or the location of the point of closest approach may be imprecise.

Moreover, the relative distance between the injector and producer wells of an X-SAGD or THAI well pair may affect potential recovery.

However, if the wells are located too near to one another, steam or air from the injector well may shunt into the producer well, and if the wells are located too far from one another, the heated heavy oil may not extend to the producer well.

Using conventional techniques, it may be difficult to accurately drill one well perpendicular to another well.

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