System for measuring multiphase fluid flow

A system for determining the flow rate of the components of a multiphase fluid flowstream such as being produced from a subterranean hydrocarbon formation, said fluid flowstream comprising primarily crude oil, water and gas, said system including:

• conduit means for receiving a main fluid flowstream from said formation and for conducting said main flowstream to a destination;
• means interposed in said conduit means for withdrawing a substantially uniform mixture of the liquid as a sample flowstream of said main flowstream;
• means for passing said sample flowstream in heat exchange relationship with a first heat exchanger means;
• second heat exchanger means for conducting said main flowstream in heat exchange relationship with a heat exchange fluid of known quantity;
• means for determining the flow rate of said sample flowstream flowing through said first heat exchanger means;
• temperature sensing means arranged with respect to said sample flowstream for sensing the temperature differential of said sample flowstream across said first heat exchanger means;
• and
• temperature sensing means arranged with respect to said main flowstream for sensing the temperature differential of said main flowstream and said heat exchange fluid through said second heat exchanger means to determine the total liquid flow rate and the total flow rate of one of the liquids of the liquid mixture.

A system for determining the flow rate of the components of a multiphase fluid flowstream such as being produced from a subterranean hydrocarbon formation, said fluid flowstream comprising a liquid mixture of primarily crude oil and water and a gas, said system including:

• conduit means for receiving a main fluid flowstream from said formation and for conducting said main flowstream to a destination;
• means interposed in said conduit means for withdrawing a substantially uniform mixture of said liquid as a sample flowstream of said main flowstream;
• heat exchanger means for conducting a heat exchange fluid of known flow rate in heat exchange relationship with said sample flowstream;
• means for reinjecting said sample flowstream into said main flowstream at a point upstream of said means for withdrawing said liquid;
• means for determining the flow rate of said sample flowstream flowing through said heat exchanger means;
• temperature sensing means arranged with respect to said sample flowstream for sensing the temperature differential of said sample flowstream across said heat exchanger means;
• and
• temperature sensing means arranged with respect to said main flowstream for sensing the temperature differential of said main flowstream between a point upstream of said point of injection and said means for withdrawing said liquid for determining the total liquid flow rate and the total flow rate of one of the liquids of the liquid mixture.

A method for determining the flow rate of components of a multiphase fluid flowstream such as a fluid flowstream being produced from a subterranean hydrocarbon formation and wherein said fluid flowstream comprises at least two liquid compositions and a gas all mixed together, said method including the steps of:

• withdrawing a sample of the fluid flowstream from time to time to determine the actual composition of the liquids and gas;
• providing conduit means for conducting said fluid flowstream, said conduit means including a first heat exchanger for exchanging heat with a main flowstream of said fluid and means for withdrawing on a substantially continuous basis a liquid sample of said fluid flowstream and a second heat exchanger for exchanging heat with said liquid sample;
• conducting said main flowstream through said first heat exchanger and measuring the temperature difference of said main fluid flowstream as determined by heat exchange with a known quantity of a known heat exchange fluid;
• conducting said sample flowstream through said second heat exchanger and measuring the heat exchanged with said sample flowstream to determine the specific heat of the liquid of said fluid flowstream;
• and
• measuring the liquid flow rate based on the flowrate of a heat exchange fluid, the specific heat of the heat exchange fluid, a temperature difference of the main flowstream flowing through said first heat exchanger means and the specific heat of the liquid mixture of said main flowstream.

A method for determining the flowrate of the liquid component and the gas component of a multiphase gas-liquid mixture flowing from a source of said mixture and wherein the composition of the components of said liquid and said gas is known, comprising the steps of:

• conducting said multiphase flowstream through a conduit means from said source;
• measuring the average density of said multiphase flowstream using density measuring means;
• and
• determining the flowrate of liquid in said main flowstream by passing at least said liquid of said main flowstream in heat exchange relationship with a heat exchange fluid of known flowrate and composition and determining the flowrate of liquid from the change in temperature of the main flowstream and the heat exchange fluid, respectively.

A method for determining the flow rate of the liquid component and the gas component of a multi-phase gas-liquid flowstream wherein the composition of the components of said liquid and said gas is known, comprising the steps of:

• conducting said multi-phase flowstream through a conduit means from a source of said gas-liquid flowstream;
• separating a sample flowstream of liquid from said multi-phase flowstream and passing said sample flow stream through means for measuring the volumetric flow rate and the mass flow rate of said sample flowstream;
• passing said sample flowstream through heat exchanger means having a source of cooling fluid of known composition and flow rate and measuring the temperature change of said cooling fluid and said sample flowstream across said heat exchanger means to determine the weight fraction of one of the liquids in said sample flowstream;
• re-injecting said sample flowstream into said multi-phase fluid flowstream;
• measuring the temperature difference of said multi-phase fluid flowstream between a point upstream of the point of re-injection of said sample flowstream and a point downstream of the point of re-injection of said sample flowstream;
• and
• determining the volumetric flow rate of liquid in the multi-phase fluid flowstream from the mass flow rate of the multi-phase fluid flowstream, the temperature difference of the sample flowstream across said heat exchanger means and the temperature difference of said multi-phase fluid flowstream between the point of re-injection of said sample flowstream and the point of separation of said sample flowstream from said multi-phase fluid flowstream.