Inter-casing pressure control systems and methods

Abstract

An apparatus and method for controlling and / or reducing undesirable and dangerous buildup of formation gases and fluids in the annular space between casing strings in an oil & gas well. The process comprises injecting a brine of cesium formate into a cement annulus between concentric well casings; and monitoring the pressure of the brine within the annulus. Based on the pressure, the flow rate of the brine being injected is controlled to displace or control formation gases and fluids within the annulus.

Description

TECHNICAL FIELD[0001]The disclosure relates to the control and / or reduction of undesirable and dangerous buildup of formation gases and fluids in the annular space between casing strings in an oil & gas well.BACKGROUND AND SUMMARY[0002]Without control of Inter-Casing Pressure (ICP, also referred to as sustained casing pressure—SCP) in an oil & gas well the possibility of an uncontrolled released of gas and fluids can occur. As this release of containment can happen with no personnel in the area of the well it is possible that the problem could quickly escalate and cause a breach in containment (loss of well integrity) which ultimately could lead to breaches in the surrounding rock structure and lead to the formation of surface vents whereby gas and oil will be released into the surrounding environment resulting in a serious Health, Safety and Environmental (HSE) problem in the area. For example, escaping hydrocarbons may be accidentally ignited. If this breakdown is below a casing s...

AI Technical Summary

Benefits of technology

This patent text describes the use of barite plugs to provide effective and low-cost pressure isolation in wellbores. Unlike cement plugs, barite plugs are easy to remove and can be used as temporary facilities for pressure isolation or as a platform enabling the accurate placement of treatments above the plug. Additionally, the patent describes a conductor casing which can prevent drilling fluids circulating outside the casing, causing surface erosion. The conductor casing acts as a protective barrier to prevent damage to the wellbore.

Problems solved by technology

Without control of Inter-Casing Pressure (ICP, also referred to as sustained casing pressure—SCP) in an oil & gas well the possibility of an uncontrolled released of gas and fluids can occur.

As this release of containment can happen with no personnel in the area of the well it is possible that the problem could quickly escalate and cause a breach in containment (loss of well integrity) which ultimately could lead to breaches in the surrounding rock structure and lead to the formation of surface vents whereby gas and oil will be released into the surrounding environment resulting in a serious Health, Safety and Environmental (HSE) problem in the area.

For example, escaping hydrocarbons may be accidentally ignited.

If this breakdown is below a casing shoe, then an influx of any kind may become unmanageable because surface controls may no longer work.

This would lead to an uncontrollable well control event.

Many governmental regulators & HSE rules around the world will not allow a well to be perforated and brought online or continue to produce while high inter-casing pressure exists.

In some cases, the only option in this case is to totally abandon this well with the loss of all the funds that have been expended to date on the actual drilling of the well and the additional funds that will be required to conduct the abandonment procedure.

Both styles of pumps require substantially more power and electronic controls to operate at a very slow speed.

As the apparatus may be working in remote areas without power available a mechanical pump would require substantially more power generation to be available on the location which could become cost prohibitive.

Also, the cost of the electronic control systems that would be required for these pumps may be cost prohibitive and maintenance intensive.

In addition, using such mechanical pumps may often result in surge pressure being induced on the annulus which we are trying to avoid so as not to pack off any particulate matter resident in the cement annulus.

The apparatus and process may also be used to control pressure in a cement annulus that has been caused by an ineffective cementing operation on the production casing string that has high inter-casing pressure (e.g. which is considered unsafe to run completion operations to bring the well online and produce oil and gas from the well).

Poor initial cementing operations

Continued erosion caused by repeated bleed down operations to reduce inter-casing pressure (or sustained casing pressure) on the well.

Images