US Patent 7604059 Downhole tools

An improved centralizer is provided for centralization of tubulars such as casings, liners, production tubing, and production screens, in oil/gas wells. Such a centralizer comprises a tubular body, wherein a portion of an outermost surface of the tubular body is formed from a first material, and a portion of, or portion adjacent to, at least one end of the tubular body, and/or a portion of an innermost surface of the tubular body, is formed from at least one second material, in contrast to unitary construction centralizers disclosed by the prior art, and the first material has a lower Young's modulus than the at least one second material.