Cuttings injection and annulus remediation systems for wellheads

In a subsea wellhead assembly having an outer wellhead housing connected to a string of conductor pipe, forming an outer wellhead assembly, an inner wellhead housing which lands in the outer wellhead housing and is connected to a first string of casing, forming an inner wellhead assembly, a casing hanger which lands on an internal landing shoulder in the inner wellhead housing and is connected to a second string of casing, the improvement comprising in combination:

• first and second passages in the inner wellhead assembly, each passage having an upper opening at an outer surface of the inner wellhead housing and a lower opening at an inner surface of the inner wellhead housing, the lower opening of the first passage being located below the landing shoulder and in communication with the annulus, the lower opening of the second passage being located above the landing shoulder;
• and
• a casing hanger passage in the casing hanger, the casing hanger passage having an upper opening at an outer surface of the casing hanger and above the landing shoulder, the casing hanger passage also having a lower opening at an outer surface of the casing hanger and below the landing shoulder;
• and
• a conduit extending alongside the casing from the lower opening of the casing hanger passage for delivering a fluid into a lower portion of the annulus;
• and wherein
• the lower opening of the second passage and the upper opening of the casing hanger passage are in communication with each other.

A method of injecting a fluid and a volume of cuttings into an annulus of a well, the method comprising;

• (a) providing a wellhead assembly having a string of casing defining a casing annulus, first and second passages leading from an exterior portion of the wellhead assembly to the annulus, and a conduit extending downward in the annulus to a selected depth, the conduit having an upper end in communication with the second passage;
• (b) flowing the fluid downward through the second passage, through the conduit, and into the annulus, the fluid displacing existing fluids in the annulus, the existing fluids flowing upward and out of the annuus through the first passage;
• and
• (c) while step (b) is not occurring, flowing a fluid containing the cuttings downward through the first passage and into the annulus.

A method of injecting a fluid and offshore well drilling cuttings into an annulus of a well, the method comprising;

• (a) installing an outer wellhead housing at a subsea floor, the outer wellhead housing being connected to a string of conductor pipe that extends into the well;
• (b) landing an inner wellhead housing in the outer wellhead housing, the inner wellhead housing having first and second passages therethrough, each passage having an upper opening at an outer surface of the inner wellhead housing and a lower opening on an inner surface of the inner wellhead housing, the lower opening of the first passage being located below an internal shoulder, the lower opening of the second passage being located above the internal shoulder;
• (c) securing a string of casing to a casing hanger and landing the casing hanger on the internal shoulder, the casing hanger having a passage sealingly communicating the lower opening of the second passage and a conduit extending alongside the casing in an annulus;
• (d) pumping a fluid into the annulus through the second passage, with existing fluid located in the annulus being forced out of the annulus through the first passage;
• and
• (e) while step (d) is not occurring, pumping cuttings into the annulus through the first passage.