Downhole device employing an electromagnet assembly having a width (wem) that is no more than 200% of a stroke distance (d) and ferromagnet assembly to actuate a movable feature

A method, comprising:

• accessing a downhole device located within a wellbore extending through one or more subterranean formations, wherein the downhole device includes:
• a member having a first member end and a second opposite member end;
• a movable element positioned about the member, the movable element having a first movable element end and a second opposite movable element end, the movable element configured to move a stroke distance (D) from a first position to a second position;
• a ferromagnet assembly fixed to one of the member or the movable element;
• and
• an electromagnet assembly fixed to an other of the movable element or the member, the electromagnet assembly having a width (WEM), wherein the width (WEM) is no more than 200% of the stroke distance (D);
• and
• supplying electric power to the electromagnet assembly to produce an electromagnetic field having an electromagnetic polarity (Y), the electromagnetic field actuating the movable element from the first position toward the second position.

A well system, comprising:

• a wellbore extending through one or more subterranean formations;
• and
• a downhole device located within the wellbore, the downhole device including:
• a member having a first member end and a second opposite member end;
• a movable element positioned about the member, the movable element having a first movable element end and a second opposite movable element end, the movable element configured to move a stroke distance (D) from a first position to a second position;
• a ferromagnet assembly fixed to one of the member or the movable element;
• and
• an electromagnet assembly fixed to an other of the movable element or the member, the electromagnet assembly having a width (WEM), wherein the width (WEM) is no more than 200% of the stroke distance (D), the electromagnet assembly operable to receive electric power to produce an electromagnetic field having an electromagnetic polarity (Y), the electromagnetic field configured to actuate the movable element from the first position toward the second position when the electromagnet assembly receives the electric power.