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US 9,453,156 B2Granted
Thermoplastic cellulosic fiber blends as lost circulation materials
AssigneeBoard of Supervisors of Louisiana State University and Agricultural and Mechanical College
InventorQinglin Wu
Life of this patent
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Abstract
A method is disclosed for reducing lost circulation in drilling wells, employing composite materials as lost circulation materials. The composites comprise a thermoplastic polymer and cellulosic fibers. Optionally the composites may include other components such as calcium carbonate, clay, oil and other blending agents.
Claims17
A method for reducing lost circulation of a fluid in a subterranean formation;
- said method comprising contacting the subterranean formation with a mixture of a fluid and a lost circulation material;
- wherein:
- (a) the lost circulation material comprises composite particles;
- (b) the composite particles comprise at least two thermoplastic polymers and cellulosic fibers;
- (c) the thermoplastic polymers are between about 10% and about 90% of the lost circulation material by mass;
- (d) at least one of the thermoplastic polymers is a common polymer, having a melting point less than 200° C.;
- and at least one of the thermoplastic polymers is an engineering polymer, having a melting point between 250° C. and 270° C.;
- (e) the cellulosic fibers are between about 10% and about 80% of the lost circulation material by mass;
- (f) the thermoplastic polymers form a matrix that binds together the other components into composite particles;
- (g) the composite particles were formed by extrusion of the components or high-speed mixing of the components, followed by grinding, cutting, or pelletizing the extruded or mixed components;
- and
- (h) the composite particles have the property that, if the composite particles are allowed to absorb water, the composite particles will swell in size while maintaining rigidity.
9 more elements
Dependencies are inferred from the claim text.