Vugular Loss Simulating Vug Tester for Screening and Evaluation of LCM Products

Abstract

An apparatus to simulate fluid loss through vugs in formations includes a housing defining an inner volume, and having a first end and a second end. The inner volume represents an inner region of a wellbore formed in a formation containing a vugular loss zone. The housing can receive wellbore fluid within the inner volume. A first cover late, which sealingly covers the first end, represents a first volumetric boundary of the inner region of the wellbore. A second cover plate, which sealingly covers the second end, represents a second volumetric boundary of the inner region of the wellbore. An outlet in the second cover plate can be switched between open and closed states. The outlet in the open state represents a vug in the inner wall of the wellbore. The apparatus includes a pressure port configured to transmit fluidic pressure in a direction of gravity within the inner volume and to apply the fluidic pressure to the wellbore fluid within the inner volume.

1 . A laboratory test apparatus comprising:
 a housing defining an inner volume, the housing comprising a first end and a second end, the inner volume representing an inner region of a wellbore at least partially formed in a formation containing a vugular loss zone of the wellbore, the housing configured to receive wellbore fluid within the inner volume;   a first cover plate configured to sealingly cover the first end, the first cover plate representing a first volumetric boundary of the inner region of the wellbore;   a second cover plate configured to sealingly cover the second end, the second cover plate representing a second volumetric boundary of the inner region of the wellbore, the second cover plate defining an outlet configured to be switched between an open state and a closed state, the outlet in the open state representing a vug in the inner wall of the wellbore; and   a pressure port configured to transmit fluidic pressure in a direction of gravity within the inner volume and to apply the fluidic pressure to the wellbore fluid within the inner volume.   
     
     
         2 . The apparatus of  claim 1 , wherein, in the open state, the outlet is configured to prevent flow of the wellbore fluid in response to the fluidic pressure, and, in the closed state, the outlet is configured to permit flow of the wellbore fluid in response to the fluidic pressure. 
     
     
         3 . The apparatus of  claim 1 , wherein a dimension of the outlet is at least 10 millimeters (mm). 
     
     
         4 . The apparatus of  claim 1 , further comprising a wired screen defining an opening, the wired screen positioned at the second end aligning the outlet and the opening, the wired screen cooperating with the second cover plate to sealingly cover the second end. 
     
     
         5 . The apparatus of  claim 1 , wherein the housing is transparent. 
     
     
         6 . The apparatus of  claim 1 , further comprising a flexible hose coupled to the outlet, the flexible hose representing a flow pathway through the vug within the vugular loss zone starting at the inner wall of the wellbore. 
     
     
         7 . The apparatus of  claim 1 , wherein the first end is an upper end and the second end is a lower end vertically below the first end, wherein the first cover plate defines an opening configured to fluidically mate with the pressure port. 
     
     
         8 . The apparatus of  claim 1 , further comprising a pressure inlet pipe coupled to the pressure port, the pressure inlet pipe configured to transmit the fluidic pressure from a pressure source into the housing through the pressure port. 
     
     
         9 . The apparatus of  claim 1 , further comprising a mounting stand attached to the first end of the housing, the mounting stand configured to maintain the housing in a substantially vertical orientation. 
     
     
         10 . A laboratory test apparatus comprising:
 a mounting stand;   a housing comprising an upper end attached to the mounting stand, the housing extending downward from the mounting stand and terminating at a lower end below the mounting stand, the housing defining an inner volume representing an annulus formed by an inner wall of a wellbore being drilled in a hydrocarbon-carrying formation and an outer wall of a drill string used to drill the wellbore, the housing comprising wellbore fluid filling the inner volume;   a lower cover plate configured to sealingly cover the lower end, the lower cover plate representing the inner wall of the wellbore, the lower cover plate defining an outlet configured to be switched between an open state and a closed state, the outlet in the open state representing a vug in the inner wall of the wellbore; and   a pressure port defined near the upper end of the housing, the pressure port configured to transmit fluidic pressure in a downward direction from the upper end towards the lower end through the wellbore fluid and to apply the fluidic pressure to the wellbore fluid within the inner volume.   
     
     
         11 . The apparatus of  claim 10 , further comprising a wired screen defining a second opening, the wired screen positioned at the second end aligning the first opening and the second opening, the wired screen cooperating with the second cover plate to sealingly cover the lower end. 
     
     
         12 . The apparatus of  claim 10 , further comprising an upper cover plate configured to sealingly cover the upper end. 
     
     
         13 . The apparatus of  claim 11 , wherein the pressure port is formed through a circumferential wall of the housing adjacent the upper cover plate. 
     
     
         14 . The apparatus of  claim 11 , wherein the pressure port is formed in the upper cover plate adjacent the housing. 
     
     
         15 . The apparatus of  claim 10 , wherein the housing is transparent. 
     
     
         16 . A method of simulating loss of wellbore fluid in a vugular loss zone, the method comprising:
 filling a housing defining an inner volume with wellbore fluid, the inner volume representing an inner region of a wellbore at least partially formed in a loss triggering subsurface formation;   sealing a first end and a second end of the housing with a first cover plate and a second cover plate, respectively, the second cover plate comprising an outlet switchable between an open state and a closed state, the outlet in the open state representing a vug in the inner wall of the wellbore;   with the outlet in the closed state, applying fluidic pressure in a direction of gravity from the first end of the housing toward the second end;   with the outlet in the open state, applying the fluidic pressure in the direction of gravity from the first end of the housing toward the second end; and   evaluating sealing and blocking properties of the wellbore fluid to flow through the vug in the inner wall of the wellbore based on a comparison of results of applying the fluidic pressure in the closed state and applying the fluidic pressure in the open state.   
     
     
         17 . The method of  claim 16 , wherein the wellbore fluid with which the inner volume is filled is a first wellbore fluid, wherein evaluating the properties of the wellbore fluid comprises:
 mixing an additive to a second wellbore fluid having a volume equal to that of the first wellbore fluid, the additive configured to alter the properties of the wellbore fluid;   filling the housing with a mixture of the second wellbore fluid and the additive;   sealing the first end and the second end of the housing with the first cover plate and the second cover plate;   with the outlet in the closed state, applying the fluidic pressure in the direction of gravity from the first end of the housing toward the second end;   with the outlet in the open state, applying the fluidic pressure in the direction of gravity from the first end of the housing toward the second end; and   evaluating the sealing and blocking properties of the wellbore fluid to flow through the vug in the inner wall of the wellbore based on a comparison of results of flow of the first wellbore fluid and the second wellbore fluid through the outlet in the open state.   
     
     
         18 . The method of  claim 16 , wherein the housing is transparent, wherein the method further comprises visually evaluating the properties of the wellbore fluid based on visual inspection of an effect of applying the fluidic pressures on the wellbore fluid in the inner volume with the outlet in the closed state and with the outlet in the open state. 
     
     
         19 . The method of  claim 16 , further comprising:
 coupling a flexible hose to the outlet, the flexible hose representing a flow pathway through the vug within a formation starting at the inner wall of the wellbore; and   visually observing flow through the flexible hose with the outlet in the open state.