Multilateral junction including an expandable sealing element

A well system, comprising:

• a main wellbore;
• a lateral wellbore extending from the main wellbore;
• and
• a multilateral junction positioned at a junction of the main wellbore and the lateral wellbore, the multilateral junction including:
• a lateral branch template having a lateral window for positioning proximate a junction between a lateral wellbore and a main wellbore;
• a lateral branch connector, a portion of the lateral branch connector extending through the lateral window;
• one or more sealing elements located in a seal groove in one of the lateral branch template or lateral branch connector, the one or more sealing elements configured to expand in volume from the seal groove into a space between the lateral branch template and the lateral branch connector to sealingly engage the lateral branch template and the lateral branch connector;
• and
• one or more fluid access ports coupling an interior of the lateral branch template and the joint between the lateral branch template and the lateral branch connector or coupling an interior of the lateral branch connector and the joint between the lateral branch template and the lateral branch connector.

A method, comprising:

• forming a main wellbore and a lateral wellbore through one or more subterranean formations;
• and
• positioning a multilateral junction at a junction of the main wellbore and the lateral wellbore, the multilateral junction including:
• a lateral branch template having a lateral window for positioning proximate a junction between a lateral wellbore and a main wellbore;
• a lateral branch connector, a portion of the lateral branch connector extending through the lateral window;
• one or more sealing elements located in a seal groove in one of the lateral branch template or lateral branch connector, the one or more sealing elements configured to expand in volume from the seal groove into a space between the lateral branch template and the lateral branch connector to sealingly engage the lateral branch template and the lateral branch connector;
• and
• one or more fluid access ports coupling an interior of the lateral branch template and the joint between the lateral branch template and the lateral branch connector or coupling an interior of the lateral branch connector and the joint between the lateral branch template and the lateral branch connector.

A multilateral junction, comprising:

• a lateral branch template having a lateral window for positioning proximate a junction between a lateral wellbore and a main wellbore;
• a lateral branch connector, a portion of the lateral branch connector extending through the lateral window;
• one or more sealing elements located in a seal groove in one of the lateral branch template or lateral branch connector, the one or more sealing elements configured to expand in volume from the seal groove into a space between the lateral branch template and the lateral branch connector to sealingly engage the lateral branch template and the lateral branch connector;
• and
• one or more valves coupling an interior and an exterior of the lateral branch template or an interior and an exterior the lateral branch connector, the one or more valves configured to allow material from within the interior of the lateral branch template or the lateral branch connector to escape as reactive fluid encounters the one or more sealing elements.