Protecting wellhead equipment from treatment fluids

A wellhead assembly, comprising:

• a production tree residing at a terranean surface of a well and coupled to a tubing spool;
• a sacrificial fluid control assembly configured to be fluidly coupled to and reside above the production tree;
• an adaptor assembly configured to be fluidly coupled to and reside between the production tree and the sacrificial fluid control assembly, the adaptor assembly configured to form, with the adaptor assembly attached to the production tree and the sacrificial fluid control assembly, a common bore defining a fluid pathway extending from the tubing spool to the sacrificial fluid control assembly;
• and
• a sleeve configured to be disposed within the common bore and extend at least from the adaptor assembly to the tubing spool, the sleeve comprising i) a first end configured to form, with the adaptor or the sacrificial fluid control assembly, a first fluid seal, and ii) a second end opposite the first end and configured to form, with the tubing spool, a second fluid seal such that the sleeve fluidly isolates a first section of the common bore from a second section of the common bore, the first section of the common bore extending from the first fluid seal to the second fluid seal;
• wherein the first section of the common bore comprises at least a portion of a bore of the tubing spool, a bore of all the production tree, and at least a portion of a bore of the adaptor assembly, and the second section of the common bore comprises at least a section of a bore of the sacrificial control assembly, the tubing spool comprising a tubing hanger comprising a back pressure valve profile, and the second end of the sleeve is configured to form, with the back pressure valve profile of the tubing hanger, a connection with the tubing hanger, the sleeve or the tubing hanger comprising one or more sealing rings to form the second fluid seal, the tubing hanger comprising an inwardly projecting shoulder that engages or stops an outwardly projecting shoulder of the sleeve.

A well assembly, comprising:

• a production tree;
• a tree cap configured to be coupled to the production tree;
• an adaptor configured to be fluidly coupled to and reside between an upper end of the production tree and a lower end of the tree cap to form a wellhead bore defining a fluid pathway extending from the production tree to the adaptor;
• and
• a sleeve configured to be disposed within the wellhead bore and extend at least from the adaptor to the production tree, the sleeve comprising i) a first portion configured to form, with the adaptor or another portion of the well assembly, a first fluid seal, and ii) a second portion configured to form, with the production tree or another portion of the well assembly, a second fluid seal such that the sleeve fluidly isolates a first section of the wellhead bore from a second section of the wellhead bore, the first section of the wellhead bore extending from the first fluid seal to the second fluid seal and comprising a bore of the production tree;
• wherein the first section of the wellhead bore comprises at least a portion of a bore of a tubing spool attached to the production tree, a bore of all the production tree, and at least a portion of a bore of the adaptor assembly, and the second section of the wellhead bore comprises at least a section of a bore of the sacrificial control assembly, the tubing spool comprising a tubing hanger comprising a back pressure valve profile, and the second portion of the sleeve is configured to form, with the back pressure valve profile of the tubing hanger, a connection with the tubing hanger, the sleeve or the tubing hanger comprising one or more sealing rings to form the second fluid seal, the tubing hanger comprising an inwardly projecting shoulder that engages or stops an outwardly projecting shoulder of the sleeve.

A method, comprising:

• disposing a sleeve within a bore of a wellhead, the wellhead comprising i) a production tree, ii) a removable sacrificial production tree configured to be fluidly coupled to and reside above the production tree, and iii) a removable adaptor configured to be fluidly coupled to and reside between the production tree and the sacrificial production tree, at least a bore of the production tree, a bore of the sacrificial production tree, and a bore of the adaptor forming the bore of the wellhead, the bore of the wellhead defining a fluid pathway extending from the production tree to the sacrificial production tree;
• and
• securing the sleeve to the adaptor such that the sleeve forms, with the adaptor or another portion of the wellhead, a first fluid seal, and the sleeve forms, with the production tree or another portion of the wellhead, a second fluid seal such that the sleeve fluidly isolates a first section of the bore from a second section of the bore, the first section of the bore extending from the first fluid seal to the second fluid seal and comprising a bore of the production tree;
• and
• flowing, from the sacrificial production tree, through the sleeve, and to a wellbore fluidly coupled to the wellhead, a treatment fluid, the first section of the bore being isolated from the treatment fluid by the sleeve,
• wherein the first section comprises at least a portion of a bore of a tubing spool attached to the production tree, a bore of all the production tree, and at least a portion of a bore of the adaptor assembly, and the second section comprises at least a section of a bore of the sacrificial control assembly, the tubing spool comprising a tubing hanger comprising a back pressure valve profile, and the second portion of the sleeve is configured to form, with the back pressure valve profile of the tubing hanger, a connection with the tubing hanger, the sleeve or the tubing hanger comprising one or more sealing rings to form the second fluid seal, the tubing hanger comprising an inwardly projecting shoulder that engages or stops an outwardly projecting shoulder of the sleeve, and the disposing comprises lowering the sleeve within the bore until the inwardly projecting shoulder stops at the outwardly projecting shoulder.

A method, comprising:

• disposing a sleeve within a bore of a wellhead, the wellhead comprising i) a production tree, ii) a removable sacrificial production tree configured to be fluidly coupled to and reside above the production tree, and iii) a removable adaptor configured to be fluidly coupled to and reside between the production tree and the sacrificial production tree, at least a bore of the production tree, a bore of the sacrificial production tree, and a bore of the adaptor forming the bore of the wellhead, the bore of the wellhead defining a fluid pathway extending from the production tree to the sacrificial production tree;
• and
• securing the sleeve to the adaptor such that the sleeve forms, with the adaptor or another portion of the wellhead, a first fluid seal, and the sleeve forms, with the production tree or another portion of the wellhead, a second fluid seal such that the sleeve fluidly isolates a first section of the bore from a second section of the bore, the first section of the bore extending from the first fluid seal to the second fluid seal and comprising a bore of the production tree;
• and
• flowing, from the sacrificial production tree, through the sleeve, and to a wellbore fluidly coupled to the wellhead, a treatment fluid, the first section of the bore being isolated from the treatment fluid by the sleeve,
• wherein the first section comprises at least a portion of a bore of the tubing spool, a bore of all the production tree, and at least a portion of a bore of the adaptor assembly, and the second section comprises at least a section of a bore of the sacrificial control assembly, the tubing spool comprising a tubing hanger comprising a back pressure valve profile, and the second end of the sleeve is configured to form, with the back pressure valve profile of the tubing hanger, a connection with the tubing hanger, the sleeve or the tubing hanger comprising one or more sealing rings to form the second fluid seal, the tubing hanger comprising an inwardly projecting shoulder that engages or stops an outwardly projecting shoulder of the sleeve, and securing the sleeve to the adaptor comprises lowering the sleeve until the outwardly projecting shoulder bears against the inwardly projecting shoulder.