Abstract: A drilling fluid containing a liquid phase, a weighting agent (e.g. barite, calcite, ilmenite), and perlite is described. The drilling fluid may further contain one or more additives including a defoamer, a fluid-loss control agent, a viscosifier, an antiscalant, a deflocculant, a lubricant, a clay stabilizer, a bridging agent, and a surfactant. A process of drilling a subterranean geological formation utilizing the drilling fluid is also specified. The introduction of perlite to the drilling fluid is effective in reducing the thickness and permeability of filter cakes formed during the drilling process.

Abstract: A barite filter cake removing composition, and single- and multi-stage methods of removing a barite filter cake from a wellbore. The composition comprises at least one polymer removal agent, at least one chelating agent, and at least one converting agent. The single-stage method includes contacting the barite filter cake with the composition to dissolve the barite filter cake from the wellbore. The multi-stage method includes contacting the barite filter cake from the wellbore with at least one polymer removal agent to remove a polymer coat present on the barite filter cake, contacting the barite filter cake with at least one converting agent to convert barium sulfate in the barite filter cake to a barium salt of carbonate, formate, cyanide, nitrate, and/or chloride, and removing the barium salt of carbonate, formate, cyanide, nitrate, and/or chloride with at least one chelating agent.

Abstract: A drilling fluid containing a liquid phase, a weighting agent (e.g. barite, calcite, ilmenite), and perlite is described. The drilling fluid may further contain one or more additives including a defoamer, a fluid-loss control agent, a viscosifier, an antiscalant, a deflocculant, a lubricant, a clay stabilizer, a bridging agent, and a surfactant. A process of drilling a subterranean geological formation utilizing the drilling fluid is also specified. The introduction of perlite to the drilling fluid is effective in reducing the thickness and permeability of filter cakes formed during the drilling process.

Abstract: A barite filter cake removing composition, and single- and multi-stage methods of removing a barite filter cake from a wellbore. The composition comprises at least one polymer removal agent, at least one chelating agent, and at least one converting agent. The single-stage method includes contacting the barite filter cake with the composition to dissolve the barite filter cake from the wellbore. The multi-stage method includes contacting the barite filter cake from the wellbore with at least one polymer removal agent to remove a polymer coat present on the barite filter cake, contacting the barite filter cake with at least one converting agent to convert barium sulfate in the barite filter cake to a barium salt of carbonate, formate, cyanide, nitrate, and/or chloride, and removing the barium salt of carbonate, formate, cyanide, nitrate, and/or chloride with at least one chelating agent.

Abstract: A method of removing an iron sulfide scale from a surface in fluid communication with a wellbore and/or subterranean formation comprising contacting the iron sulfide scale on the surface with a composition to dissolve the iron sulfide scale in the composition. The composition comprises (a) at least one chelating agent selected from the group consisting of DTPA, EDTA HEDTA, GLDA, CDTA, and MGDA, and salts thereof, and (b) at least one converting agent selected from the group consisting of potassium carbonate (K2CO3), potassium formate (HCOOK), potassium hydroxide (KOH), potassium chloride (KCl), cesium formate (HCOOCs), and cesium chloride (CsCl). In the composition, the weight ratio of (a):(b) lies in the range 7-60:2-20.

Abstract: A barite filter cake removing composition, and single- and multi-stage methods of removing a barite filter cake from a wellbore. The composition comprises at least one polymer removal agent, at least one chelating agent, and at least one converting agent. The single-stage method includes contacting the barite filter cake with the composition to dissolve the barite filter cake from the wellbore. The multi-stage method includes contacting the barite filter cake from the wellbore with at least one polymer removal agent to remove a polymer coat present on the barite filter cake, contacting the barite filter cake with at least one converting agent to convert barium sulfate in the barite filter cake to a barium salt of carbonate, formate, cyanide, nitrate, and/or chloride, and removing the barium salt of carbonate, formate, cyanide, nitrate, and/or chloride with at least one chelating agent.

Abstract: A drilling fluid system using retarded acid systems such as gelled acid (VES or polymer) and/or emulsified acid to drill carbonate formations (calcite and dolomite). Foamed acid may be used in low abnormal pressure carbonate reservoirs. The drilling fluid system permits drilling a target hydrocarbon-producing formation with zero-invasion of the drilling fluid system. A method for using the drilling fluid system for fluid loss control during drilling operations.

Abstract: A method of removing an iron sulfide scale from a surface in fluid communication with a wellbore and/or subterranean formation comprising contacting the iron sulfide scale on the surface with a composition to dissolve the iron sulfide scale in the composition. The composition comprises (a) at least one chelating agent selected from the group consisting of DTPA, EDTA HEDTA, GLDA, CDTA, and MGDA, and salts thereof, and (b) at least one converting agent selected from the group consisting of potassium carbonate (K2CO3), potassium formate (HCOOK), potassium hydroxide (KOH), potassium chloride (KCl), cesium formate (HCOOCs), and cesium chloride (CsCl). In the composition, the weight ratio of(a):(b) lies in the range 7-60:2-20.

Abstract: A method of removing an iron sulfide scale from a surface in fluid communication with a wellbore and/or subterranean formation comprising contacting the iron sulfide scale on the surface with a composition to dissolve the iron sulfide scale in the composition. The composition comprises (a) at least one chelating agent selected from the group consisting of DTPA, EDTA, HEDTA, GLDA, CDTA, and MGDA, and salts thereof, and (b) at least one converting agent selected from the group consisting of potassium carbonate (K2CO3), potassium formate (HCOOK), potassium hydroxide (KOH), potassium chloride (KCl), cesium formate (HCOOCs), and cesium chloride (CsCl). In the composition, the weight ratio of (a):(b) lies in the range 7-60:2-20.

Abstract: A drilling fluid system using retarded acid systems such as gelled acid (VES or polymer) and/or emulsified acid to drill carbonate formations (calcite and dolomite). Foamed acid may be used in low abnormal pressure carbonate reservoirs. The drilling fluid system permits drilling a target hydrocarbon-producing formation with zero-invasion of the drilling fluid system. A method for using the drilling fluid system for fluid loss control during drilling operations.

Abstract: A method of removing an iron sulfide scale from a surface in fluid communication with a wellbore and/or subterranean formation comprising contacting the iron sulfide scale on the surface with a composition to dissolve the iron sulfide scale in the composition. The composition comprises (a) at least one chelating agent selected from the group consisting of DTPA, EDTA, HEDTA, GLDA, CDTA, and MGDA, and salts thereof, and (b) at least one converting agent selected from the group consisting of potassium carbonate (K2CO3), potassium formate (HCOOK), potassium hydroxide (KOH), potassium chloride (KCl), cesium formate (HCOOCs), and cesium chloride (CsCl). In the composition, the weight ratio of (a):(b) lies in the range 7-60:2-20.

Abstract: A barite filter cake removing composition, and single- and multi-stage methods of removing a barite filter cake from a wellbore. The composition comprises at least one polymer removal agent, at least one chelating agent, and at least one converting agent. The single-stage method includes contacting the barite filter cake with the composition to dissolve the barite filter cake from the wellbore. The multi-stage method includes contacting the barite filter cake from the wellbore with at least one polymer removal agent to remove a polymer coat present on the barite filter cake, contacting the barite filter cake with at least one converting agent to convert barium sulfate in the barite filter cake to a barium salt of carbonate, formate, cyanide, nitrate, and/or chloride, and removing the barium salt of carbonate, formate, cyanide, nitrate, and/or chloride with at least one chelating agent.

Abstract: A drilling fluid system using retarded acid systems such as gelled acid (VES or polymer) and/or emulsified acid to drill carbonate formations (calcite and dolomite). Foamed acid may be used in low abnormal pressure carbonate reservoirs. The drilling fluid system permits drilling a target hydrocarbon-producing formation with zero-invasion of the drilling fluid system. A method for using the drilling fluid system for fluid loss control during drilling operations.

Abstract: A drilling fluid system using retarded acid systems such as gelled acid (VES or polymer) and/or emulsified acid to drill carbonate formations (calcite and dolomite). Foamed acid may be used in low abnormal pressure carbonate reservoirs. The drilling fluid system permits drilling a target hydrocarbon-producing formation with zero-invasion of the drilling fluid system. A method for using the drilling fluid system for fluid loss control during drilling operations.