Downhole gas/water separation and re-injection

A production fluid handling method comprising the steps:

• providing a horizontal gravity gas\liquid separator and sloping downwards the gas\liquid separator in a direction of flow of fluid produced from an underground formation;
• separating downhole at least gaseous and liquid components of the produced fluid by horizontal gravity separation;
• and
• at least one of (i) injecting at least a proportion of the separated gaseous component back into the formation, and (ii) producing at least a proportion of the gaseous component to the surface.

A production fluid handling method comprising the steps:

• separating downhole at least gaseous and liquid components of fluid produced from an underground formation by horizontal gravity separation;
• injecting at least a proportion of the separated gaseous component back into the formation;
• compressing gas downhole at or around formation or reservoir depth using a multi-stage axial flow compressor driven by a multi-stage axial flow turbine;
• and
• powering the turbine by power liquid delivered under pressure from surface.

Apparatus for production fluid handling, the apparatus comprising:

• a downhole horizontal fluid separator for separating at least gaseous and liquid components of fluid produced from an underground formation,
• a downhole gas compressor for injecting at least a portion of the gaseous component back into the formation;
• and
• a separated gas collector comprising an elongate tube positioned in the gas/liquid separator, wherein an upstream end of the elongate tube gas collector is tapered from a tube upper surf ace to a tube lower surface.

Apparatus for production fluid handling, the apparatus comprising:

• a downhole horizontal fluid separator for separating at least gaseous and liquid components of fluid produced from an underground formation;
• a downhole gas compressor for injecting at least a portion of the gaseous component back into the formation;
• and
• a separated gas collector comprising an elongate tube positioned in the gas/liquid separator, wherein a lower surface of the elongate tube gas collector is substantially planar.

Apparatus for production fluid handling, the apparatus comprising:

• a downhole horizontal fluid separator for separating at least gaseous and liquid components of fluid produced from an underground formation;
• a downhole gas compressor for injecting at least a portion of the gaseous component back into the formation;
• and
• a separated gas collector comprising an elongate tube positioned in the gas/liquid separator, wherein an upstream end of the elongate tube oil collector is tapered from a tube upper surface to a tube lower surface.

Apparatus for production fluid handling, the apparatus comprising:

• a downhole horizontal fluid separator for separating at least gaseous and liquid components of fluid produced from an underground formation;
• a downhole gas compressor for injecting at least a portion of the gaseous component back into the formation;
• a separated gas collector comprising an elongate tube positioned in the gas/liquid separator;
• and
• a separated oil collector in the form of an elongate tube positioned in an upper portion of the oil/water separator, wherein a lower surface of the elongate tube oil collector is substantially planar.

Apparatus for production fluid handling, the apparatus comprising:

• a downhole horizontal fluid separator for separating at least gaseous and liquid components of fluid produced from an underground formation;
• a downhole gas compressor for injecting at least a portion of the gaseous component back into the formation;
• and
• a separated water collector in the form of an elongate tube positioned in a lower portion of the oil/water separator, wherein the horizontal fluid separator further comprises an oil/water separator, and an array of holes is provided in a lower surface of the elongate tube water collector to allow collection of water.

Apparatus for production fluid handling, the apparatus comprising:

• a downhole horizontal fluid separator for separating at least gaseous and liquid components of fluid produced from an underground formation;
• a downhole gas compressor for injecting at least a portion of the gaseous component back into the formation;
• and
• a separated water collector in the form of an elongate tube positioned in a lower portion of the oil/water separator, wherein the horizontal fluid separator further comprises an oil/water separator, and a lower surface of the elongate tube water collector is substantially planar.