Patent Application
20170058670
This specification relates to fluid sampling containers, for example, containers for sampling hydrocarbons recovered from a hydrocarbon reservoir, hydrocarbon pipeline, refining process, or fiscal sales point.
Hydrocarbons trapped in hydrocarbon reservoirs can be recovered using wellbores formed through the hydrocarbon reservoirs. The hydrocarbons recovered from the reservoirs are tested, for example, at different times during production, stabilization, processing, and custody transfer. In this manner, properties of the recovered hydrocarbons, for example, chemical composition, volume fractions, or other properties, can be determined. Such tests are conducted in laboratories that are often at locations different from locations of the wellbores, transmission pipelines, processing plants, or sales points. Therefore, a hydrocarbon sample recovered from a sample collection point is transported to the laboratory for testing. The properties of the sample may change during transportation. For example, non-miscible fluids suspended in the collected sample may separate and heavier density miscible phases may stratify. In such instances, the collected sample will no longer produce laboratory sub-samples that accurately represent the properties of the sample from the collection point.
This specification describes technologies relating to a liquid sampling container with an internal mixer.
Certain aspects of the subject matter described here can be implemented as a fluid sampling container. The container includes a sealed outer body configured to hold a sample multi-phase fluid obtained from a multi-phase fluid stream. An inlet line is attached to the outer body. The sample multi-phase fluid flows into the sealed outer body through the inlet line. A piston assembly is positioned within the sealed outer body. The piston assembly is sealed to the inner walls of the outer body to define a sample volume in which the sample multi-phase fluid is contained. A shear mixer is positioned within the sealed outer body. The shear mixer includes a rotor and a stator arranged to define a fluid passage and rotatable relative to each other. The rotor includes a rotary shear blade configured to shear the sample multi-phase fluid such that a homogeneity of multiple phases in the sample multi-phase fluid remains substantially constant.
This, and other aspects, can include one or more of the following features. The piston assembly can include a front axial end and a rear axial end. The front axial end can be nearer to the inlet line than the rear axial end. The shear mixer can be positioned between the front axial end and the inlet line. The stator can be a hollow, stationary stator within which the rotary shear blade can be positioned. The rotor is rotatable to rotate the rotary shear blade within the hollow, stationary stator. A drive shaft can rotate the rotary shear blade. The drive shaft can pass through the piston assembly and can extend outside the outer body. The stator can include a mesh screen attached to a circumferential surface of the stator. The sample multi-phase fluid sheared by the rotary shear blade in the fluid passage can exit the shear mixer through the mesh screen. A position of the shear mixer between the piston assembly and the inlet line can be adjustable. The position of the shear mixer can be adjustable to be abutted against the front axial end of the piston assembly or be spaced apart from the front axial end of the piston assembly. The piston assembly and the shear mixer can be positioned within a housing. The piston assembly can include a floating piston. A magnetic ring can be attached to a circumference of the floating piston. A magnetic tracker can be attached to an outside surface of the outer body. The magnetic tracker can track a position of the floating piston within the outer body. A temperature detector can be connected to the piston assembly. The temperature detector can determine a temperature of the sample multi-phase fluid and provide the determined temperature as a wireless signal to a display and storage unit. Heating coils can be mounted to an exterior of the sealed outer body. The heating coils can be configured to heat the sample multi-phase fluid. The inlet line can be attached to the outer body through an inlet end cap. An inlet pressure gauge can be connected to the inlet end cap. The inlet pressure gauge can include a wireless transmitter configured to transmit a pressure measured by the inlet pressure gauge. A display unit can be configured to receive and display the pressure transmitted by the wireless transmitter. A purge line can be attached to the outer body. Contents of the sealed outer body can be purged through the purge line before the sample multi-phase fluid flows into the sealed outer body through the inlet line. The multi-phase fluid stream can include hydrocarbons drawn from a hydrocarbon reservoir. The sample multi-phase fluid can include aqueous and hydrocarbon liquids. A controller can be connected to the shear mixer. The controller can be configured to operate the shear mixer to continuously mix the sample multi-phase fluid at mixing conditions at which the homogeneity of multiple phases in the sample multi-phase fluid remains substantially constant over time. The controller can be configured to operate the shear mixer to continuously mix the sample multi-phase fluid at the mixing conditions such that a cumulative distribution of the multiple phases in the sample multi-phase fluid volume remains substantially constant over time. The container, at least partially filled with the sample multi-phase fluid, is portable from a first physical location to a second physical location.
Certain aspects of the subject matter described here can be implemented as a method. A fluid container is at least partially filled with a sample multi-phase fluid drawn from a multi-phase fluid stream. The fluid container includes a sealed outer body configured to hold the sample multi-phase fluid. An inlet line is attached to the outer body. The sample multi-phase fluid flows into the sealed outer body through the inlet line. A piston assembly is positioned within the sealed outer body. The piston assembly is sealed to inner walls of the outer body to define a sample volume in which the sample multi-phase fluid is contained. A shear mixer is positioned within the sealed outer body. The shear mixer includes a rotor and a stator arranged to define a fluid passage and rotatable relative to each other. The rotor includes a rotary shear blade configured to shear the sample multi-phase fluid such that a homogeneity of multiple phases in the sample multi-phase fluid remains substantially constant over time. The shear mixer is operated to mix the sample multi-phase fluid such that a homogeneity of multiple phases in the sample multi-phase fluid remains substantially constant over time.
This, and other aspects, can include one or more of the following features. The fluid container is portable from a first physical location at which the sample multi-phase fluid is collected to a second physical location to which the sample multi-phase fluid is delivered. The shear mixer can be operated to mix the sample multi-phase fluid such that a concentration of each multi-phase component in the sample multi-phase fluid at the first physical location is substantially equal to a concentration of each multi-phase component in the sample multi-phase fluid at the second physical location. The multi-phase fluid stream can include hydrocarbons drawn from a hydrocarbon reservoir. The sample multi-phase fluid can include aqueous and hydrocarbon liquids.
Certain aspects of the subject matter described here can be implemented as a fluid container. The fluid container includes a sealed outer body configured to hold a sample multi-phase fluid drawn from a multi-phase fluid stream at a first physical location for transporting to a second physical location in the fluid container. The fluid container includes a shear mixer positioned within the sealed outer body. The shear mixer includes a rotor and a stator arranged to define a fluid passage and rotatable relative to each other. The rotor includes a rotary shear blade configured to shear the sample multi-phase fluid flowing through the fluid passage. The shear mixer is configured to shear the sample multi-phase fluid such that a homogeneity of multiple phases in the sample multi-phase fluid remains substantially constant while transporting the multi-phase fluid stream from the first physical location to the second physical location.
This, and other aspects, can include one or more of the following features. The fluid container can include a controller connected to the shear mixer. The controller can operate the shear mixer to mix the sample multi-phase fluid such that a concentration of each multi-phase component in the sample multi-phase fluid at the first physical location is substantially equal to a concentration of each multi-phase component in the sample multi-phase fluid at the second physical location. The multi-phase fluid stream can include hydrocarbons drawn from a hydrocarbon reservoir. The sample multi-phase fluid can include aqueous and hydrocarbon liquids.
The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.
Like reference numbers and designations in the various drawings indicate like elements.
Changes in pressure or temperature can create compositional changes of the fluids collected in a sample cylinder. Constant pressure sampling containers prevent phase change of fluids from the sample state by maintaining a constant pressure within the cylinder. In instances in which the fluids include volatile materials, such as crude oil, the constant pressure can prevent loss of light end components from the liquid phase while a sample fluid is being held in the sampling container for a sampling period. Crude oil can also be a multi-phase fluid that includes suspensions of aqueous fluids (water-based liquids and vapors), solids (sediment), and hydrocarbon fluids (that is, hydrocarbon-based liquids and vapors). During transportation, for example, from a collection site to a laboratory, the immiscible components and phases will separate, thereby biasing any sub-sample collected from the sampling container.
Certain atmospheric sampling containers include an external motorized pump that circulates the sample using a static mixer to homogenize the sample. However, mixing volatile crude oil under atmospheric conditions can result in loss of light ends, thereby changing the chemical composition of the sample. Proper mixing of the multi-phase, volatile liquids in constant pressure containers under these conditions can minimize or avoid the loss of light ends during sub-sampling at the laboratory. In such containers, separation of immiscible phases (water from oil) does occur, so homogeneity of the multi-phase sample needs to be maintained without compromising the sample integrity, for example, during storage or while transporting the sample between locations.
This specification describes techniques to provide homogeneous mixing of a sample multi-phase fluid carried in a constant pressure fluid sampling container. Implementations of the techniques described here allow sampling multi-phase fluids, for example, volatile multi-phase fluids such as hydrocarbons, directly from a reservoir wellhead or downstream process. The physical state or integrity of the sample multi-phase fluid, for example, the composition of the sample, can be retained. For example, minimal or no change in the physical state or integrity of the sample multi-phase fluid will be observed between sample collection and sample testing at a laboratory. The conditions of the sample multi-phase fluid, for example, volume, temperature, pressure, and other conditions, at the laboratory can be returned to the conditions at the time of sample drawing. In this manner, sample integrity and sample homogenization can simultaneously be maintained by the following: preventing phase change within the sample which compromises mixture integrity; preventing stratification within the sample has the potential to cause erroneous analytical results; returning constant pressure cylinders to the original fluid temperature and pressure of original sampling conditions.
In the example schematic diagram shown in
The fluid sampling container can be implemented to maintain compositional homogeneity of the multi-phase fluid sample, for example, as the multi-phase fluid sample is transported from a first physical location (for example, the well site 120) to a second physical location (for example, the laboratory 122). Homogeneity of the multi-phase fluid sample is maintained when the percentage of components is equally distributed throughout the sample cylinder volume. Homogeneity is also maintained by preventing any change in distribution of liquid volatile components from flashing to a gaseous state. In the context of a sample transfer, the cumulative distribution of the multi-phase components (for example, the solids, aqueous and hydrocarbon liquids and vapor phase components) obtained at time of collection from the reservoir or process stream under in-situ conditions represents the cumulative distribution of the multi-phase components in the laboratory sub-sample
The fluid sampling container described here maintains homogeneity by mixing (for example, continuously mixing) the multi-phase fluid sample such that aqueous and hydrocarbon droplets are substantially equally sized and substantially equally distributed throughout the cylinder sample volume. The mixing elements described here are internal to the fluid sampling container, thereby eliminating or minimizing the possibility of changes to the volume or composition of the sample that can result when implementing atmospheric external mixing elements, external pressurized mixing elements, or internal mixing elements which change the original volume sample size.
The container 200 includes an inlet line 206 attached to the outer body 202 via the cylinder inlet end cap 250. In some implementations, the outer body 202 can include externally mounted heating coils 280 and controllers for heating the sample cavity. The inlet end cap 250 can include an inlet pressure gauge 256. The inlet pressure gauge 256 can include wireless, analog, battery-powered transmitter with local display/memory storage unit 262. The transmitter can provide data to the local display/memory storage unit 262. The inlet end cap 250 can also include a pressure relief valve 259 for inlet cavity 257. As shown in
The sample multi-phase fluid 204 flows into the sealed inlet cylinder cavity 257 through inlet line 206. Inlet cylinder cavity 257 creates the sample volume in which the sample multi-phase fluid 204 is contained. Prior to sampling, the cylinder piston assembly 208 is forced to the cylinder inlet end cap 250. This is accomplished by venting the volume of the inlet cylinder cavity 257 through inlet line 206 by opening the inlet valve 253 or through the purge valve 220, and by back pressuring the cylinder with an inert gas (such as nitrogen or helium) through back pressure valve 252. Back pressure is maintained in the back pressure cavity by closing the back pressure valve 252. Backpressure can be monitored using back pressure gauge 254. The back pressure gauge 254 can also be a wireless, analog, battery-powered transmitter with local pressure readout. The transmitter can provide measured data to the local display/memory storage unit 262. The outlet end cap 255 can include a pressure relief valve 259 for back pressure cavity 251. The volume of the inlet cylinder cavity 257 resulting between the cylinder piston assembly 208 and cylinder inlet end cap 250 can be purged prior to introducing sample into the cylinder through the sample purge line valve 220.
To fill the cylinder with the sample multi-phase fluid, the backpressure of the back pressure cavity 251 is relieved through backpressure valve 252 until equilibrium pressure is reached through the inlet line 206. At this point, sample will enter inlet cylinder cavity 257 through inlet valve 206 at the process operating pressure of the hydrocarbon pipeline stream. Sample will continue to fill the inlet cylinder cavity until the back pressure valve 252 is closed at approximately 80% of the cylinder total volume.
The container 200 includes a piston assembly 208 positioned within the sealed outer body 202. The piston assembly 208 includes a free floating piston 240 and creates a seal to inner walls 210 of the outer body 202 by O-ring gaskets 258. The piston assembly 208 also separates inlet cylinder cavity 257 from back pressure cavity 251.
In some implementations, a magnetic ring 242 can be attached to a circumference of the floating piston 240. For example, the magnetic ring 242 can surround substantially (for example, all or less than all of) an entirety of the circumference of the floating piston 240. An external magnetic tracker 244 can be attached to an outside surface track 263 on the outer body 202. The magnetic tracker 244 can track the position of the floating piston 240 within the outer body 202 by tracking a position of the magnetic ring 242.
In some implementations, the piston assembly 208 is tracked by the position of the drive shaft 218 attached to the internal floating piston assembly through the cylinder outlet end cap 255 to the back end of the piston cylinder. As shown in
As shown in
As described below and shown in
The shear mixer 212 is abutted against cylinder inlet end cap 250 and is flush facing to the front axial end 214 of the piston assembly 208, as shown in
In some implementations, as shown in
At 501, the pressure cylinder is prepared for sampling. For example, the outlet cavity is back pressured to a pressure exceeding the line pressure from which the sample will be collected. By opening the inlet purge valve, the piston will travel to the inlet cylinder cap at the front of the cylinder. The purge valve and sample inlet valves are closed and the backpressure valves used to charge the cylinder are also closed.
At 502, sample multi-phase fluid is drawn from a multi-phase stream. For example, during sampling, the cylinder is connected directly to the sample tap, fast loop connection piping, or tubing. The sample tap valve is opened and the dead volume of the sample line and cylinder inlet sample cavity is purged. This is accomplished by opening the inlet sample valve and flushing the system through the inlet purge valve into a waste collection container until the line and cylinder deadspace volume is confirmed to be adequately flushed. The purge valve is now closed and the inlet sample cavity will increase to line pressure. The sample cylinder backpressure is slowly reduced through the backpressure valve, allowing the piston to slowly travel backward to the cylinder end cap, filling the inlet sample cavity volume with sample. The back pressure purge valve is closed when 80% of the cylinder sample volume or less is reached by the floating piston and the inlet sample valve is closed. The sample temperature, pressure, and piston shaft position are recorded manually from local display or automatically recorded in the local system memory temperature and pressure systems or recorded electronically from the end caps may be screwed into the inlet and backpressure valves for transport. While the process is envisioned to be a manual operation, the system can be automated through the controller 246 by opening the inlet line and releasing the precharge backpressure to draw the sample multi-phase fluid into the container 200.
At 503, the sample multi-phase fluid, for example, sample hydrocarbons drawn from a hydrocarbon stream or sample process streams drawn from source process streams, can be transported from a physical location in which they are collected to a laboratory for testing. The sample can be returned to sample process conditions by heating the cylinder to the original line temperature using the integrated heating coils or through external means. This will return the piston position to the original noted location and bring the sample cylinder back to the original line conditions. Once the original physical line conditions have been satisfied, the sample can be mixed using the internal shear mixer for homogenization. At 503, while the system is envisioned to be mixed at the destination facility, the internal mixing elements can continuously mix the sample multi-phase fluid in a closed environment during transportation to maintain the homogeneity of the sample during the duration of transportation.
At 504, the sample multi-phase fluid is mixed in the container using a shear mixer positioned in the container. For example, the controller 246 can control the shear mixer 212 to shear the sample multi-phase fluid 204 such that a homogeneity of multiple phases in the sample multi-phase fluid 204 remain substantially constant over time. The controller 246 can be configured, for example, by an operator, to operate the shear mixer 212 at different operational conditions (for example, rotation, speed, duration, or other operational conditions). Based on the properties of the sample multi-phase fluid (for example, viscosity, pressure, vapor pressure, physical properties, or other properties), the controller 246 can be controlled to select a set of operational conditions under which the sample multi-phase fluid can be continuously mixed. For example, the operational conditions of the shear mixer 212 can be varied based on the sample multi-phase fluid properties to satisfy Section 8.3 (Standard Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products) or Appendix B.4 (Acceptance Criteria for Insertion Mixers) of the American Petroleum Institute (API) Manual of Petroleum Measurement Standards (MPMS).
As the shear mixer 212 is an internal mixing element of a constant pressure fluid sampling container, mixing of the sample multi-phase fluid occurs in a closed system of original volume, pressure and temperature. Consequently, there will be no loss of material, no change in phase from liquid to vapor, and no loss of volatile components. Such mixing in a closed system in a steady state avoids three problems associated with such mixing—loss of water through water vapor, loss of light ends phases. In addition, the use of the shear mixer 212 can homogenize any emulsion phases and ensure uniform droplet size throughout the sample matrix. Moreover, the compositional volume of the sample multi-phase fluid remains substantially constant over time. Therefore, the original sampled pressure and volume can be re-established at a duration after the sample has been collected. For example, the original sample temperature can be returned by controlled heating of the sample cylinder in an oven, water bath, or electrically controlled heating assembly.
At 505, the sample multi-phase fluid is transported in the fluid sample container from a first physical location to a second physical location. As described above, the sample multi-phase fluid, for example, sample hydrocarbons drawn from a hydrocarbon stream or sample process streams drawn from source process streams, can be transported from a physical location in which they are collected to a laboratory for testing. The internal mixing elements can continuously mix the sample multi-phase fluid in a closed environment during transportation to maintain the homogeneity of the sample during the duration of transportation.
Thus, particular implementations of the subject matter have been described. Other implementations are within the scope of the following claims.
