Patent Publication Number: US-10309201-B1

Title: Method, apparatus, and system for injecting chemicals into lower tertiary wells

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/815,873, filed on Nov. 17, 2017, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Many conventional sources of oil and gas production are on the decline. As a result, it has become more difficult and expensive to extract these reserves. To meet expected demand, the industry has increasingly focused on unconventional sources as it has become more technically and economically feasible to do so. According to the International Energy Agency, at least 10% of the remaining recoverable conventional oil and gas reserves lie below the seafloor in deep water. In offshore drilling operations, a drilling rig is typically used to drill a wellbore to recover oil or gas reserves disposed below the seafloor. The offshore facilities may include bottom founded, floating, or mobile drilling rigs and production platforms. In ultra-deepwater operations, drilling and production is conducted in water depths between 5,000 and 10,000 feet or more. Conventionally, offshore operations drill wellbores having a measured depth in excess of 10,000 feet. 
     The Lower Tertiary is an informal designation for a layer of the Earth&#39;s crust deposited during the Paleogene period, between 65 and 23 million years ago. The Gulf of Mexico&#39;s Lower Tertiary is considered one of the largest ultra-deepwater oil and gas reserves. According to recent estimates, the Gulf of Mexico&#39;s Lower Tertiary is believed to contain between 10 and 40 billion barrels of oil equivalent (“BBOE”). This is significant given that the total estimate of U.S. oil and gas reserves is currently estimated to be approximately 30 BBOE. However, extracting oil and gas from the Lower Tertiary presents a number of technical and economic challenges. To access these reserves, ultra-deepwater drilling operations must deal with water depths up to 10,000 feet or more and drill a further 15,000 to 30,000 feet or more below the seafloor, often under thick sheets of salt, to reach Lower Tertiary reserves. At depth, the downhole temperature may exceed 400° F. and formation pressure may exceed 25,000 pounds per square inch (“PSI”) further complicating production activities, including chemical injection. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one aspect of one or more embodiments of the present invention, a chemical injector for injecting chemicals into a Lower Tertiary well includes a housing and a chemical injection port. The housing includes a first threaded opening that extends into a portion of a first cavity, a second threaded opening that extends into a portion of a second cavity, a control port that fluidly connects the first cavity to the second cavity, and a communication port that fluidly connects the second cavity to a chemical outlet port. The chemical injection port includes an inlet end configured to receive fluid flow and an outlet end that directs the fluid flow to the control port. The chemical injection port is inserted into the first threaded opening. A bottom plug is inserted into the second threaded opening. A bellows having a first distal end connected to the bottom plug and a second distal end connected to a dart configured to controllably open and close the communication port. An application of a predetermined amount of fluid pressure to the chemical injection port compresses the bellows and withdraws the dart from the communication port, allowing fluid flow to the chemical outlet port. 
     According to one aspect of one or more embodiments of the present invention, a chemical injection mandrel for injecting chemicals into a Lower Tertiary well includes a mandrel and a chemical injector disposed on an exterior surface of the mandrel. The mandrel includes a hollow interior passageway and a mandrel injection port. The chemical injector includes a housing. The housing includes a first threaded opening that extends into a portion of a first cavity, a second threaded opening that extends into a portion of a second cavity, a control port that fluidly connects the first cavity to the second cavity, and a communication port that fluidly connects the second cavity to a chemical outlet port. The chemical injector includes a chemical injection port having an inlet end configured to receive fluid flow and an outlet end that directs the fluid flow to the control port. The chemical injection port is inserted into the first threaded opening. The chemical injector includes a bottom plug inserted into the second threaded opening and a bellows having a first distal end connected to the bottom plug and a second distal end connected to a dart configured to controllably open and close the communication port. Application of a predetermined amount of fluid pressure to the chemical injection port compresses the bellows and withdraws the dart from the communication port, allowing fluid flow to the chemical outlet port and into the hollow interior passageway of the mandrel via the mandrel injection port. 
     According to one aspect of one or more embodiments of the present invention, a subsea system for injecting chemicals into a Lower Tertiary well includes a fluid system disposed on a floating production storage and offloading unit, production tubing disposed in a wellbore, a chemical injection mandrel disposed on a distal or near-distal end of the production tubing, and a chemical injection line disposed in an annulus between the production tubing and the wellbore that fluidly connects the fluid system and a chemical injector of the chemical injection mandrel. The chemical injection mandrel includes a mandrel having a hollow interior passageway and a mandrel injection port. The chemical injector is disposed on an exterior surface of the mandrel. The chemical injector includes a housing. The housing includes a first threaded opening that extends into a portion of a first cavity, a second threaded opening that extends into a portion of a second cavity, a control port that fluidly connects the first cavity to the second cavity, and a communication port that fluidly connects the second cavity to a chemical outlet port. The chemical injector includes a chemical injection port having an inlet end configured to receive fluid flow from the chemical injection line and an outlet end that directs the fluid flow to the control port. The chemical injection port is inserted into the first threaded opening. The chemical injector includes a bottom plug inserted into the second threaded opening, and a bellows having a first distal end connected to the bottom plug and a second distal end connected to a dart configured to controllably open and close the communication port. An application of a predetermined amount of fluid pressure to the chemical injection port compresses the bellows and withdraws the dart from the communication port, allowing fluid flow to the chemical outlet port and into the hollow interior passageway of the mandrel via the mandrel injection port. 
     According to one aspect of one or more embodiments of the present invention, a method of injecting chemicals into a Lower Tertiary well includes connecting a chemical injection line between a fluid system and a chemical injector of a chemical injection mandrel, attaching the chemical injection mandrel to a distal or near-distal end of production tubing, disposing the production tubing into a wellbore, wherein the chemical injection line is disposed in an annulus between the production tubing and the wellbore, and applying fluid pressure in the chemical injection line to enable fluid flow through the chemical injector of the chemical injection mandrel and into a hollow interior passageway of a mandrel of the chemical injection mandrel. 
     According to one aspect of one or more embodiments of the present invention, a chemical injection mandrel for injecting chemicals through an annularly disposed control line includes a housing attached to production tubing and a chemical injector disposed in the housing. The chemical injector includes a seat, a dart, biasing means, and a porting system. The biasing means biases the dart on seat. The porting system uses hydrostatic pressure in the control line to assist keeping the dart on seat. The porting system directs fluid from the control line to unseat the dart when fluid is to be provided downhole. 
     Other aspects of the present invention will be apparent from the following description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a subsea system for injecting chemicals into a Lower Tertiary well in accordance with one or more embodiments of the present invention. 
         FIG. 1B  shows a cross-section of the wellbore showing the chemical injection line for the chemical injection mandrel in the annulus between the production tubing and the wellbore in accordance with one or more embodiments of the present invention. 
         FIG. 2A  shows a front-facing perspective view of a chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 2B  shows a side elevation view of the chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 2C  shows a rear-racing perspective view of the chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 3  shows an exploded front-facing perspective view of a chemical injector of a chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 4A  shows a side cross-sectional view of a chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 4B  shows a side cross-sectional detail view of a portion of a chemical injector of the chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 4C  shows a top cross-sectional view of the chemical injector of the chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 4D  shows a cross-sectional view of one or more control ports and a communication port of the chemical injector of the chemical injection mandrel in accordance with one or more embodiments of the present invention. 
         FIG. 5A  shows a top cross-sectional detail view of a chemical injector of a chemical injection mandrel showing fluid communication in accordance with or more embodiments of the present invention. 
         FIG. 5B  shows a side cross-sectional detail view of the chemical injector of the chemical injection mandrel showing fluid communication in accordance with or more embodiments of the present invention. 
         FIG. 5C  shows a side cross-sectional view of the chemical injection mandrel showing fluid communication in accordance with or more embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One or more embodiments of the present invention are described in detail with reference to the accompanying figures. For consistency, like elements in the various figures are denoted by like reference numerals. In the following detailed description of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention. In other instances, well-known features to one of ordinary skill in the art are not described to avoid obscuring the description of the present invention. 
     During production operations, chemicals are injected downhole to optimize production flow and minimize the need for expensive interventions. Conventional chemical injection systems are used to inject various chemicals including, for example, corrosion and scale inhibitors, surfactants, asphaltines, hydrates, emulsions, demulsifiers, scavengers, paraffins, weighting agents, and other chemicals. In various operations, expensive chemicals are continuously provided downhole. When the hydrostatic pressure of the wellbore is balanced by the formation pressure, chemicals can be injected at a fairly uniform rate controlled by the chemical injection pump. However, over time, when the formation pressure drops as a result of production, the pressure imbalance causes the formation to syphon chemicals at a substantially higher rate than desired, potentially up to ten times the normal amount, at substantial expense. 
     In land-based wells, conventional chemical injection systems use a chemical injection pump to inject chemicals downhole via a chemical injection mandrel disposed within the production tubing. Certain conventional chemical injection mandrels reduce chemical flow when the hydrostatic pressure falls to prevent the syphoning of chemicals downhole. These conventional chemical injection mandrels are disposed within the production tubing and at substantially shallower depths. However, they are not suitable for use in ultra-deepwater wells drilled in the Lower Tertiary. Because of the downhole temperature, the downhole pressure, and the hydrostatic head, conventional chemical injection systems are sensitive to production tubing pressure and cannot operate in the harsh conditions where the temperature may exceed 400° F. and pressures may exceed 25,000 PSI. To date, there is no known chemical injection system for effectively injecting chemicals bottomhole in the Lower Tertiary. As such, there is a long felt and unsolved need in the industry for a chemical injection method, apparatus, and system for wells drilled in the Lower Tertiary. 
     Accordingly, in one or more embodiments of the present invention, a method, apparatus, and system for injecting chemicals into a Lower Tertiary well allows for the efficient and controlled delivery of chemicals downhole in a manner that is production tubing pressure insensitive. A chemical injection mandrel includes a chemical injector disposed on an exterior surface of a mandrel. The chemical injection mandrel connects to the production tubing, such that the chemical injector portion of the chemical injection mandrel is disposed in the annulus between the production tubing and the wellbore. A floating production storage and offloading (“FPSO”) unit on the surface of the water may include a chemical injection pump that injects chemicals downhole via a chemical fluid line that runs in the annulus between the production tubing and the wellbore. The chemical fluid line connects to the chemical injector portion of the chemical injection mandrel and delivers chemicals to the interior passageway of mandrel of the chemical injection mandrel where the chemicals mix with the production flow directed to the surface. Advantageously, the method, apparatus, and system for injecting chemicals into a Lower Tertiary well allow for the efficient and controlled delivery of expensive chemicals downhole in a manner that is pressure insensitive. 
       FIG. 1A  shows a subsea system  100  for injecting chemicals into a Lower Tertiary well in accordance with one or more embodiments of the present invention. During ultra-deepwater operations in the Lower Tertiary, a FPSO  102  may be disposed on the surface of the water  104 . An umbilical  106  may connect a fluid system (not shown) disposed on the FPSO  102  to a header  108 . The header  108  may connect umbilical  106  to a subsea umbilical  110  that may be connected to a subsea wellhead  162 , disposed at a depth of 5,000 feet or more. The subsea umbilical  110  may include a chemical injection line  112  that is directed into a wellbore  118  drilled into the subsea ground  114 . The wellbore  118  may have a measured depth in excess of 15,000 feet and perhaps as much as 30,000 feet or more, to allow access to Lower Tertiary reserves. A portion of the wellbore  118  may be cased  122  up to a certain depth, substantially shallower than the measured depth of the well. The chemical injection line  112  may be disposed in the annulus  130  between production tubing  126  and wellbore  118 . At a certain depth, one or more packers  130  with a feed-through port  138  may be disposed in the annulus between production tubing  126  and casing  122  to seal annulus  130 . Feed-through port  138  may allow chemical injection line  112  to bypass packer  130  while maintaining the annular  130  seal. 
     A chemical injection mandrel  200  may be disposed on a distal or near-distal end of production tubing  126  downhole. The chemical injection line  112  may fluidly connect a fluid system (not shown) disposed on the FPSO  102  on the surface of the water  104  to the chemical injection mandrel  200 , the connection being made in the annulus  130  (see, for example,  FIG. 1B ). The specific gravity of the chemical in the chemical injection line  112  creates a pressure head  142  between the FPSO  102  and the formation  146 . The pressure head  142  is balanced by the formation  146  pressure. As pressure in the formation  146  declines over time, the pressure head  142  increases, creating a syphoning of the chemical. In the Lower Tertiary, conditions at the bottom of the wellbore  118  may be extremely harsh. Temperatures may exceed 400° F. and pressures may exceed 25,000 PSI. In addition, various parts of the formation (not independently illustrated) may exhibit different temperatures and pressures and the temperatures and pressures may change over time. As discussed in the background, changes in formation pressure may result in a syphoning action that draws substantially more chemicals if the chemical injection system is sensitive to wellbore pressure. 
     In one or more embodiments of the present invention, the chemical injection mandrel  200  allows for the efficient and controlled delivery of chemicals  154  downhole in a manner that is pressure insensitive. In certain embodiments, the hydrostatic head  142  acts through a porting system comprised of one or more control ports ( 408  of  FIG. 4 ), a communication port ( 416  of  FIG. 4 ), and a chemical outlet ( 412  of  FIG. 4 ) to keep a dart ( 228  of  FIG. 5A ) on seat (small opening of communication port  416  of  FIG. 4 ) instead of acting to open it. The fluids system (not shown) disposed on the FPSO  102  may direct chemicals  154  through chemical injection line  112  into chemical injection mandrel  200 . Upon the application of a predetermined amount of fluid pressure in chemical injection line  112 , chemical injection mandrel  200  may direct chemicals  154  into an interior passageway of a mandrel (not independently illustrated) of chemical injection mandrel  200  via a mandrel injection port (not independently illustrated). The chemicals  154  may then mix with production flow  150  from the formation. The mixture  158  of the chemicals  154  and the production flow  150  may return to the surface via the subsea wellhead  162  and a production flow line  166  that may be directed to the FPSO  102  for further processing or storage. Because of the design of the chemical injection mandrel  200  and disposition of the chemical injector portion of chemical injection mandrel  200  and chemical injection line  112  in the annulus  130 , the application of fluid pressure, and the injection of chemicals at or near the bottom of the hole, is tubing pressure insensitive. As such, the fluid flow rate of chemicals  154  may be controlled by the fluids system (not shown) disposed on the FPSO  102 , independent of the tubing pressure or changes therein. Continuing,  FIG. 1B  shows a cross-section of the wellbore  118  showing the chemical injection line  112  for the chemical injection mandrel  200  in the annulus  130  between the production tubing  126  and the wellbore  118  in accordance with one or more embodiments of the present invention. 
       FIG. 2A  shows a front-facing perspective view of a chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. Chemical injection mandrel  200  may include a mandrel  206  and a chemical injector  210  disposed around an exterior surface of the mandrel  206 . Mandrel  206  may include a first threaded end  202  configured to connect to a distal end of production tubing (e.g.,  126  of  FIG. 1A ) and a second threaded end  230  for potential connection to other equipment, such as, for example, a production packer (e.g.,  168  of  FIG. 1A ). One of ordinary skill in the art will recognize that the equipment that may be connected to the second threaded end  230  may vary based on the application or design in accordance with one or more embodiments of the present invention. Mandrel  206  may include a hollow interior passageway  204  for fluid flow therein. Chemical injector  210  may include a housing  214  disposed about the exterior surface of mandrel  206 . A chemical injection port  212  (partially shown) may be inserted into a portion of a first cavity (not independently illustrated) of housing  214  of chemical injector  210  and may be configured to receive a chemical injection line (e.g.,  112  of  FIG. 1 ). Continuing,  FIG. 2B  shows a side elevation view of the chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. Continuing,  FIG. 2C  shows a rear-racing perspective view of the chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. A bottom plug  216  (partially shown) may be inserted into a portion of a second cavity (not independently illustrated) of housing  214  of chemical injector  210 . 
       FIG. 3  shows an exploded front-facing perspective view of a chemical injector  210  of a chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. Chemical injector  210  may include a housing  214  disposed about an exterior surface of mandrel  206 . A chemical injection port  212  may be inserted into a first threaded opening  213  (partially shown) that extends into a portion of a first cavity (partially shown) of housing  214 . A crush ring  220  may create a seal between chemical injection port  212  and first threaded opening  213  of housing  214  when chemical injection port  212  is fully inserted into first threaded opening  213 . A first distal end of nitrogen-charged bellows  224  may be fixedly attached to bottom plug  216 . A second distal end of a bellows  224  may be fixedly attached to a dart  228 . The assembled bottom plug  216 , bellows  224 , and dart  228  subassembly (not shown) may be inserted into a second threaded opening (not shown) that extends into a portion of a second cavity (not shown) of housing  214 . In certain embodiments, biasing means, such as, for example, a spring (not shown), a coil spring (not shown), a wave spring (not shown), or belleville washers (not shown) may be used instead of bellows  224 . A crush ring  220  may create a seal between bottom plug  216  and the second threaded opening (not shown) of housing  214  when bottom plug  216  is fully inserted into the second threaded opening (not shown). 
       FIG. 4A  shows a side cross-sectional view of a chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. In this view, hollow interior passageway  204 , which extends from distal end to distal end, of mandrel  206  is shown. Continuing,  FIG. 4B  shows a side cross-sectional detail view of a portion of chemical injector  210  of chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. Chemical injection port  212  may be configured to receive a chemical injection line (e.g.,  112  of  FIG. 1 ) that directs fluid flow (not shown) to an inlet end  402  of chemical injection port  212 . Inlet end  402  may direct fluid flow (not shown) to an outlet end  403  that directs fluid flow (not shown) into a portion of a first cavity  404 . One or more control ports  408  (shown as dashed lines in this cross-sectional view) may direct fluid flow (not shown) to a portion of a second cavity  410  that envelopes bellows  224 . When the fluid pressure applied at chemical injection port  212  is less than a predetermined amount, bellows  224  may be in an uncompressed or biased state assisted by the pressure of the hydrostatic head and dart  228  is on seat, closing communication port  416 , thereby preventing fluid flow (not shown) into a chemical outlet  412 . When a predetermined amount of fluid pressure is applied (not shown) to chemical injection port  212 , the fluid pressure within the portion of the second cavity  410  causes bellows  224  to compress, withdrawing dart  228  off seat, and opening communication port  416 , thereby directing fluid flow (not shown) from communication port  416  to chemical outlet  412  and into the hollow interior passageway (e.g.,  204  of  FIG. 4A ) of the mandrel (e.g.,  206  of  FIG. 4A ) via a mandrel injection port  418 . As such, communication port  416  may be controllably opened or closed based on an amount of fluid pressure applied to chemical inlet  402  of chemical injection port  212 . A plug  424  may be used to seal the drill hole used to create chemical outlet  412 . One of ordinary skill in the art will recognize that the predetermined amount of fluid pressure required to withdraw dart  228  may vary based on an application or design in accordance with one or more embodiments of the present invention. In addition, one of ordinary skill in the art will recognize that the predetermined amount of fluid pressure required to withdraw dart  228  may be controlled by varying one or more of the diameter of inlet end  402 , the diameter of outlet end  403 , the size and shape of first cavity  404 , the size and shape of control ports  408 , the size and shape of second cavity  410 , and the characteristics of a type or kind of bellows  224  used. 
     Continuing,  FIG. 4C  shows a top cross-sectional detail view of the portion of chemical injector  210  of chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. In this view, the one or more control ports  408  that fluidly connect the first cavity  404  to the second cavity  410  are shown. In addition, a hemispherical interface between communication port  416  and chemical outlet  412  is shown. Continuing,  FIG. 4D  shows a cross-sectional view of one or more control ports  408  that fluidly connect the first cavity (not shown) and the second cavity (not shown) of the housing  214  and a communication port  416  of the chemical injector  210  of the chemical injection mandrel  200  in accordance with one or more embodiments of the present invention. In addition, ghost lines show chemical outlet  412  in relation to communication port  416 . As noted above, in one or more embodiments of the present invention, there is a hemispherical interface between communication port  416  and chemical outlet  412 . 
       FIG. 5A  shows top cross-sectional detail view of a chemical injector  210  of a chemical injection mandrel  200  showing fluid communication in accordance with or more embodiments of the present invention. A chemical injection line (e.g.,  112  of  FIGS. 5B and 5C ) may connect to an inlet end  402  of a chemical injection port  212  and may direct chemical fluid flow  154  under controllable pressure provided by a fluid system (not shown) disposed on, for example, a FPSO (e.g.,  102  of  FIG. 1A ) on the surface of the water. Chemical fluid flow  154  may traverse the chemical injection port  212  from inlet end  402  to outlet end  403 , where chemical fluid flow  154  may be directed to a portion of a first cavity  404  of housing  214  of chemical injector  210 . Chemical fluid flow  154  may be directed from the portion of the first cavity  404  into one or more control ports  408  that fluidly connect the first cavity  404  to the second cavity  410 . When the predetermined amount of fluid pressure is applied, the fluid pressure within the second cavity  410  may compress bellows  224 , withdrawing dart  228  off seat and opening communication port  416  to chemical fluid flow  154 . 
     Continuing,  FIG. 5B  shows side cross-sectional detail view of chemical injector  210  of chemical injection mandrel  200  showing fluid communication in accordance with or more embodiments of the present invention. While dart  228  is off seat, chemical fluid flow  154  may be directed from communication port  416  to chemical outlet  412 . Chemical outlet  412  may direct chemical fluid flow  154  into an interior passageway  204  of a mandrel  206  of chemical injection mandrel  200  via a mandrel injection port  418  that fluidly connects chemical outlet  412  and interior passageway  204  of mandrel  206 . Continuing,  FIG. 5C  shows side cross-sectional view of the chemical injection mandrel  200  showing fluid communication in accordance with or more embodiments of the present invention. While dart  228  is off seat, chemical fluid flow  154  enters hollow interior passageway  204  of mandrel  206  and mixes with production flow  150  entering the bottomhole oriented distal end of mandrel  206 . Chemical fluid flow  154  and production flow  150  mix and the production flow with injected chemicals  158  traverse and exit mandrel  206 , up the production tubing (e.g.,  126  of  FIG. 1A ) to the production flow line (e.g.,  166  of  FIG. 1A ) that returns the fluids to the FPSO (e.g.,  102  of  FIG. 1A ) on the surface for further processing or storage. 
     In one or more embodiments of the present invention, a method of injecting chemicals into a Lower Tertiary well may include connecting a chemical injection line between a fluid system and a chemical injector of a chemical injection mandrel. The chemical injection mandrel may be attached to a distal end of production tubing. The production tubing may be disposed in a wellbore. The chemical injection line may be disposed in the annulus between the production tubing and the wellbore. Fluid pressure may be applied to the chemical injection line to enable chemical fluid flow through the chemical injector of the chemical injection mandrel and into a hollow interior passageway of a mandrel of the chemical injection mandrel. Specifically, the application of fluid pressure in the chemical injection line may direct chemical fluid flow into an inlet end of a chemical injection port of the chemical injector of the chemical injection mandrel. Chemical fluid flow into the inlet end of the chemical injection port may direct chemical fluid flow from a first cavity of the chemical injector into a second cavity of the chemical injector by way of one or more control ports that fluidly connect the first cavity to the second cavity. Upon application of a predetermined amount of fluid pressure, fluid flow into the second cavity may cause a bellows of the chemical injector to compress and withdraws a dart from a communication port of the chemical injector, allowing chemical fluid flow from the second cavity into the communication port. Chemical fluid flow from the communication port may be directed to a chemical outlet port of the chemical injector and into a hollow interior passageway of the mandrel via a mandrel injection port. The chemical fluid flow into the mandrel injection port of the mandrel allows for chemical fluid flow to be mixed with production flow provided by formation fluids in the hollow interior passageway of the mandrel. The mixture of production flow and chemical fluid flow are directed up the production tubing towards the surface via a production flow line that returns fluids to the FPSO on the surface of the water. 
     Advantages of one or more embodiments of the present invention may include one or more of the following: 
     In one or more embodiments of the present invention, a method, apparatus, and system for injecting chemicals into a Lower Tertiary well allows for the efficient and controlled injection of chemicals into Lower Tertiary wells in a manner that is tubing pressure insensitive. 
     In one or more embodiments of the present invention, a method, apparatus, and system for injecting chemicals into a Lower Tertiary well allows the fluid flow rate of chemical injection to be controlled from the surface in a manner that is production tubing pressure insensitive. If the formation pressure falls and the formation syphons fluids, the fluid flow rate through the chemical injector is substantially unchanged. Advantageously, this prevents the formation from drinking large amounts of expensive chemicals and saves the attendant expense. 
     In one or more embodiments of the present invention, a method, apparatus, and system for injecting chemicals into a Lower Tertiary well uses a chemical injector disposed in the annulus between the production tubing and the wellbore. The chemical injection line that connects the fluids system disposed on the FPSO to the chemical injector disposed downhole is also disposed in the annulus. As such, the fluids system disposed on the surface may control the rate of chemical fluid flow by application of fluid pressure within the chemical injection line in a manner that is tubing pressure insensitive. 
     In one or more embodiments of the present invention, a method, apparatus, and system for injecting chemicals into a Lower Tertiary well uses a chemical injector that is normally closed and only opens when a predetermined amount of fluid pressure is provided from the surface. As such, the effect of downhole pressure is substantially reduced or eliminated, thereby preventing chemicals from inadvertently flowing into the formation when downhole pressures suddenly decrease. Advantageously, the fluid flow rate of chemicals can be controlled from the surface by application of fluid pressure. 
     In one or more embodiments of the present invention, a method, apparatus, and system for injecting chemicals into a Lower Tertiary well uses a chemical injector having a hemispherical interface between the communication port and the chemical outlet port. 
     In one or more embodiments of the present invention, a method, apparatus, and system for injecting chemicals into a Lower Tertiary well uses a chemical injector having a bellows that functions at extremely high temperatures and pressures. 
     While the present invention has been described with respect to the above-noted embodiments, those skilled in the art, having the benefit of this disclosure, will recognize that other embodiments may be devised that are within the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the appended claims.