The problem of lost circulation occurs almost permanently during drilling operations. When drilling highly permeable, highly fractured, and depleted zones, large drilling fluid losses lead to increased operational expenses. Lost circulation may have several consequences, including fluid inflow, wellbore collapse, formation damage, nonproductive rig time, and environmental issues. In the last century, lost circulation has presented great challenges to the petroleum industry, requiring large capital expenditures and time to address the problem. A particular challenge is depleted reservoirs. As the reserves decline, pore pressure decreases, resulting in weakened hydrocarbon-bearing rocks; nearby or inter-bedded low permeability rocks, however, may maintain their pore pressure. This situation can make the drilling of certain depleted zones extremely difficult. Generally, the fluid density necessary to support the shale above exceeds the fracture resistance of the sands, silts, or carbonates below. Consequently, it is vital to design the drilling fluid to minimize mud invasion into formation and prevent lost circulation, and to provide the possibility of removal at a later stage (completion).

To mitigate circulation loss risks, a broad range of treatments and preventive methods using lost circulation material (LCM) have been tried and recommended over the years with varying degrees of success and efficiency. This paper presents an extensive review of the applications of various technologies, both proven and potential, in LCM for sandstone and carbonate depleted reservoirs. It describes the state of the art, advantages, limitations, and suggested specific applications. It also presents recent references of their uses in the petroleum industry and discusses the application and the status of the technologies.

For sandstone, the materials discussed focus on LCM in the form of flakes, granules, fibers, blends of these materials, particulate materials, polyglycolic acid (PGA) and polylactic acid (PLA) materials, as well as nanoparticles (NP) and nanocomposites. For carbonate formations, the scope includes conventional LCM, such as cement plugs, settable plugs, polyurethane grouting and other new technologies, such as gels, viscoelastic surfactant gels (VES), and crosslinked gels.

This review compiles crucial information necessary to design and formulate the fluid using LCM for the depleted reservoir challenges.

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