A fluid seal assembly consists of a seal element of compliant material that is retainingly carried by a seal carrier. The seal carrier includes one or more elements of relatively rigid material defining a sealing face with a seal-receiving groove interrupting the sealing face. The seal-receiving groove has groove-defining walls each of which has a proximal end at the sealing face and a distal end. The groove-defining walls serve as seal contact surfaces. The seal contact surfaces are configured such that the seal-receiving groove narrows toward its distal end. The seal-receiving groove has a depth and a breadth suitable for accepting the seal element, with the seal element projecting past the sealing face when compressed to be in contact with the seal contact surfaces.