Annular fluid manipulation in lined tubular systems to enhance component mechanical properties and flow integrity

A method of treating fluids in an annulus, comprising the steps of:

• providing a fluid-circulation space in an annulus between a host tubular and a liner therein;
• detecting an undesired fluid in the annulus;
• and then
• circulating a benign fluid through the fluid-circulation space and to the location of said undesired fluid;
• wherein said benign fluid reacts with and thereby neutralizes said undesired fluid;
• and
• wherein said undesired fluid is an acid or a precursor of an acid and said benign fluid reduces an effect of said acid on the host pipe.

A method of treating fluids in an annulus, comprising the steps of:

• providing a fluid-circulation space in an annulus between a host tubular and a liner therein;
• detecting an undesired fluid in the annulus;
• and then
• reducing pressure in said annulus sufficiently to reduce the concentration of said undesired fluid to an acceptable level.

A method of reducing propensity for propagation of cracks in a host tubular, comprising the steps of:

• providing a liner within said host tubular, said liner and host tubular having a fluid-circulating space provided therebetween;
• determining a safe pressure which can be applied by a gaseous or multi-phase fluid to said host tubular without causing substantial propagation of cracks in said host tubular;
• providing a fluid in a bore within said liner at a pressure greater than said safe pressure;
• and
• manipulating a fluid in said fluid-circulating space so that its pressure is at a level below said safe pressure.

A method of increasing structural stiffness of a liner in a tubular system, comprising the steps of:

• providing a liner within a host tubular, said liner and host tubular having a fluid-circulating space provided therebetween;
• determining a safe pressure which can be applied within the annulus without collapsing the liner or rupturing the host tubular;
• providing a fluid in said fluid-circulating space at a pressure level below said safe pressure, and further
• providing said fluid in said fluid-circulating space at conditions enabling an increase of structural stiffness properties of the liner.