Pump control for formation testing
First Claim
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1. A method for controlling a pumping system of a formation fluid sampling tool during formation fluid sampling, comprising:
- collecting in situ measurements from at least one sensor in the tool; and
using the measurements in adaptive feedback loops to control performance of the pumping system.
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Abstract
A downhole formation fluid pumping and a sampling apparatus are disclosed that may form part of a formation evaluation while drilling tool or part of a tool pipe string. The operation of the pump is optimized based upon parameters generated from formation pressure test data as well as tool system data thereby ensuring optimum performance of the pump at higher speeds and with greater dependability. New pump designs for fluid sampling apparatuses for use in MWD systems are also disclosed.
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Citations
25 Claims
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1. A method for controlling a pumping system of a formation fluid sampling tool during formation fluid sampling, comprising:
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collecting in situ measurements from at least one sensor in the tool; and using the measurements in adaptive feedback loops to control performance of the pumping system. - View Dependent Claims (2, 3, 4, 5)
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6. A method for controlling a pumping system of a formation fluid sampling tool during formation fluid sampling, comprising:
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(a) obtaining formation or formation fluid pressure test data; (b) determining another formation or formation fluid parameters using the pressure test data; (c) determining a desired pump parameter based on the other parameter; (d) determining an expected formation response to sampling the formation, wherein the expected formation response is determined based on the other formation parameter and the desired pump parameter; (e) predicting maximum power available from a turbine or turbo-alternator of the pumping system; (f) controlling operation of the pumping system based on the predicted maximum power available, electrical load limitations of the pumping system determined from torque limitations of the pumping system, mechanical load limitations of the pumping system, and losses in the pumping system; (g) updating parameters of the pumping system as controlling operation of the pumping system proceeds; (h) updating operation of the pumping system based on the updated parameters according to the desired pump parameters, under the control of prevailing operational conditions determined in one or more previous steps; (i) measuring the formation response to sampling by the tool; and (j) comparing the measured formation response to the expected formation response. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for controlling a pumping system of a formation fluid sampling tool during formation fluid sampling, comprising:
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(a) obtaining formation or formation fluid pressure test data; (b) determining another formation or formation fluid parameters using the pressure test data; (c) determining a desired pump parameter based on the other parameter, wherein the desired pump parameter is a control sequence for the pumping system, wherein the control sequence is formulated as prescribed pressure levels, pressure variations, and/or flow rates of the pumping system, wherein the control sequence is formulated as a function of time or volume, and wherein the control sequence comprises an investigation phase and a storage phase; (d) determining an expected formation response to sampling the formation, including generating a formation model, wherein the expected formation response is determined based on the other formation parameter and the desired pump parameter, wherein the formation model relates a drawdown pressure differential as a function of formation flow rate, wherein the formation model is parameterized by overbalance and mobility of the formation fluid, wherein the formation model comprises a parameter describing depth of invasion by mud filtrate, and wherein the formation model predicts evolution of gas-oil ratio or contamination level for a plurality of sampling scenarios; (e) predicting maximum power available from a turbine or turbo-alternator of the pumping system, including using a model for the turbine or turbo-alternator, wherein the model for the turbine or turbo-alternator comprises power curves each expressing generated power as a function of angular velocity; (f) controlling operation of the pumping system based on the predicted maximum power available, electrical load limitations of the pumping system determined from torque limitations of the pumping system, mechanical load limitations of the pumping system, and losses in the pumping system; (g) updating parameters of the pumping system as controlling operation of the pumping system proceeds; (h) updating operation of the pumping system based on the updated parameters according to the desired pump parameters, under the control of prevailing operational conditions determined in one or more previous steps; (i) measuring the formation response to sampling by the tool, including measuring a flow line pressure and a pump flow rate and then computing formation flow rate with a tool model; (j) comparing the measured formation response to the expected formation response; (k) using a fluid analysis module to provide feedback in the form of optical densities at different wavelengths to compute a gas-oil ratio of the sampled fluid, to monitor contamination of the sampled fluid, or to detect bubbles or sand in the flow line; and (l) monitoring a fluid property to detect if the sample fluid that enters the tool comes in single phase, such that the sampling pressure is not below the bubble point or the dew precipitation of the formation fluid; wherein steps (g) and (h) comprise; if the desired pump parameters meet the operational conditions, the desired pump parameters are used to update the pump operation; if not, operational condition limits are used to update the pump operation.
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Specification