Focused formation fluid sampling probe

A method for retrieving a formation fluid from a formation surrounding a wellbore having a contaminating fluid, comprising:

• conveying a formation tester into the wellbore, said formation tester defining a probe zone and a guard zone adjacent the formation;
• controlling the pressures of the probe zone and guard zone such that the guard zone pressures is the same as or lower than the probe zone pressure;
• and
• retrieving formation fluid from the probe zone.

A method for retrieving a formation fluid from a formation surrounding a wellbore having a drilling fluid comprising:

• conveying a formation tester into the wellbore, said formation tester defining a probe zone and a guard zone adjacent the formation;
• operating the formation tester to retrieve fluid from the guard zone and reducing the flow of the drilling fluid into the probe zone;
• and
• retrieving fluid from the probe zone;
• connecting a guard flow line to the guard zone;
• connecting a probe flow line to the probe zone;
• and
• lowering the pressure in the guard flow line to below the pressure of the probe flow line.

A formation tester tool for retrieving a formation fluid from a formation surrounding a wellbore having a drilling fluid, comprising:

• a probe adapted to retrieve the formation fluid from a first (probe) zone in the formation;
• a probe flow line associated with the probe:
• a guard ring, said guard ring defining a second (guard) zone adjacent the probe zone;
• a guard flow line associated with the guard ring;
• a first pump adapted to control pressure in the probe flow line;
• and
• a second pump adapted to control pressure in the guard flow line.
• a device for retrieving fluid from the guard zone in order to reduce the flow of the drilling fluid into the probe zone.

A formation tester tool for retrieving a formation fluid from a formation surrounding a wellbore having a drilling fluid comprising:

• a probe adapted to contact said the formation and retrieve the formation fluid from a first (probe) zone in the formation;
• a guard ring, said guard ring defining a second (guard) zone adjacent the probe zone;
• a guard flow line connected to the guard zone for retrieving fluid from the guard zone;
• a probe flow line connected to the probe zone;
• and
• a first control device for controlling fluid flow into the probe flow line and a second control device for controlling fluid flow into the guard flow line, wherein the first control device maintains a first pressure in the probe flow line and the second control device maintains a second pressure in the guard flow line, the first pressure being greater than or equal to the second pressure.

A formation tester tool for retrieving a formation fluid from a formation surrounding a wellbore having a drilling fluid, comprising:

• a probe adapted to retrieve the formation fluid from a first (probe) zone in the formation;
• a guard ring said guard ring defining a second (guard) zone adjacent the probe zone;
• and
• a device for retrieving fluid from the guard zone in order to reduce the flow of the drilling fluid into the probe zone;
• a probe flow line in fluid communication with the probe zone;
• a first control device for controlling fluid flow into the probe flow line;
• and
• a second control device for controlling fluid flow into the guard flow line;
• wherein the first control device maintains a first pressure in the probe flow line and the second control device maintains a second pressure in the guard flow line, the first pressure being greater than or equal to the second pressure.

A fluid sampling tool for retrieving a first fluid from a first zone where an adjacent second zone has a second fluid, comprising:

• a tool body having a first chamber the first chamber adapted to receive the first fluid;
• a probe having a first portion for penetrating the first zone, the probe having a probe flow line in fluid communication with the first chamber;
• the probe flow line having a first controlled flow rate;
• and
• a guard ring circumferentially disposed around the probe, the guard including a guard flow line, the guard flow line having a second controlled flow rate the first and second controlled flow rates varied such that the flow of the second fluid into the first zone is reduced.

A formation tester tool for retrieving a formation fluid from a formation surrounding a wellbore having a drilling fluid, comprising:

• (a) a first element adapted to retrieve the formation fluid from a first probe zone in the formation, the first element having a first controlled pressure;
• and
• (b) an isolation device, said isolation device defining, a second zone adjacent the probe zone, the isolation device having a second controlled pressure the first pressure being greater than or equal to the second pressure, thereby creating a fluid retrieval condition where the flow of drilling fluid into the first probe zone is reduced;
• and
• (c) a device for retrieving formation fluid from the second zone.

A method for retrieving a formation fluid from a formation surrounding a wellbore having a contaminating fluid, comprising:

• positioning a formation tester in the wellbore, said formation tester defining a probe zone and a guard zone adjacent the formation;
• varying the pressure in the probe zone and guard zone such that the contaminating fluid is drawn from the formation into the guard zone, thereby creating a fluid retrieval condition where the flow of contaminating fluid into the probe zone is reduced;
• and
• retrieving formation fluid from the probe zone.