Fluid injection system and method

A scale squeeze injection system, comprising:

• a production tree, comprising:
• a first end having a mandrel with a mandrel bore and an annular external profile encircling a mandrel axis;
• a second end having a production bore and attached to a well having production tubing in the well and a tubing annulus surrounding the production tubing;
• a tubing annulus passage extending from the tubing annulus to a tubing annulus mandrel flowpath extending from the mandrel bore;
• a tubing annulus master valve in the tubing annulus passage;
• a tubing annulus access valve in the tubing annulus passage between the tubing annulus mandrel flowpath and the tubing annulus master valve;
• a production outlet passage leading from the production tubing for connection to a flow line;
• a production wing valve in the production outlet passage for selectively opening and closing the production outlet passage;
• a crossover passage having a tubing annulus end that joins the tubing annulus passage at a point between the tubing annulus master valve and the tubing annulus access valve, the crossover passage having a production outlet passage end that joins the production outlet passage at a point between the production tubing and the production wing valve;
• a crossover valve in the crossover passage;
• a connector connects to the external profile of the mandrel;
• a scale squeeze supply line attached to the connector so that the scale squeeze supply line is in fluid communication with the mandrel bore above the tubing annulus mandrel port;
• wherein
• the tree having an injection mode with the annulus access valve open, the tubing annulus master valve closed, the crossover valve open, and the production wing valve closed, defining a flow path communicating the fluid supply line with the production tubing via the mandrel bore, the tubing annulus mandrel flowpath, the tubing annulus passage, the crossover passage, and a portion of the production outlet passage between the production wing valve and the production tubing;
• and
• the tree having a production mode with the annulus access valve closed, the tubing annulus master valve closed, the crossover valve closed, and the production wing valve open, defining a flow path communicating the production tubing with the flow line.

A method of injecting fluid into a well, comprising:

• providing a production tree with a mandrel having a mandrel bore, a production outlet passage, a production wing valve in the production outlet passage, a tubing annulus passage leading to the tubing annulus mandrel flowpath extending from the mandrel bore, an annulus access valve in the tubing annulus passage, and a crossover passage having a tubing annulus end that joins the tubing annulus passage and a production passage end that joins the production outlet passage;
• connecting the production tree to a well so that the production outlet passage of the tree is in fluid communication with production tubing in the well and a tubing annulus surrounding the production tubing is in fluid communication with the tubing annulus passage;
• connecting a fluid supply line to an upper portion of the mandrel of the tree;
• opening the annulus access valve and closing the production wing valve, providing an injection mode fluid path from the fluid supply line into the mandrel bore, through the tubing annulus mandrel flowpath, the tubing annulus passage and the crossover passage to the production outlet passage and into the production tubing;
• while in the injection mode, injecting fluid through the fluid supply line, into the production outlet passage of the tree, and into the production tubing of the well;
• and
• closing the annulus access valve and opening the production wing valve, providing a production mode fluid path from the production tubing through the production wing valve.