Inflatable packer with prestressed bladder

An inflatable packer for positioning downhole from a tubular string and for sealing downhole in a wellbore, the packer comprising:

• a packer tube for supporting at the tubular string in the wellbore;
• an upper packer sub and a lower packer sub each supported on the packer tube;
• and
• an elastomeric bladder extending between the upper packer sub and the lower packer sub, the bladder prior to inflation being axially pre-stretched at least 10% beyond its unstretched length;
• a reinforcement layer surrounding at least a portion of the bladder for engaging an inner wall of the wellbore;
• and
• a sleeve-shaped cover surrounding at least a portion of the reinforcement layer and having an end spaced axially from both the upper packer sub and the lower packer sub to expose a portion of the reinforcement layer.

An inflatable packer for positioning downhole from a tubular string and for sealing downhole in a wellbore, the packer comprising:

• a packer tube for supporting at the tubular string in the wellbore;
• supporting an upper packer sub and a lower packer sub on the packer tube;
• axially stretching an elastomeric bladder between the upper packer sub and the lower packer sub to a pre-stretched length according to the approximation:
• S≧n*(RE−RN)/L*100%,
• where
• S=stretch of the bladder (%);
• n=maximum number of folds along the length of the bladder;
• RE=radius of engagement of the bladder when packer is inflated in the borehole;
• RN=nominal radius of the tubular bladder;
• and
• L=length of the bladder.

An inflatable packer for positioning downhole from a tubular string and for sealing downhole in a wellbore, the packer comprising:

• a packer tube for supporting at the tubular string in the wellbore;
• an upper packer sub and a lower packer sub each supported on the packer tube;
• and
• an elastomeric bladder extending between the upper packer sub and the lower packer sub, the bladder prior to inflation being axially pre-stretched at least 10% beyond its unstretched length;
• a reinforcement layer surrounding at least a portion of the bladder for engaging an inner wall of the wellbore;
• both the upper packer sub and the lower packer sub being fixed axially with respect to the packer tube;
• a reinforcement layer surrounding at least a portion of the bladder for engaging an inner wall of the wellbore;
• and
• a radial thickness of the bladder prior to being axially stretched is greater than a radial spacing between an OD of the packer tube and an ID of the reinforcement layer, such that the bladder is axially stretched to fit within the radial spacing.