The downhole sensor readings of the MRDP are periodically compared with a known reference for the master calibration. At the wellsite, sensor readings are compared in a before-survey calibration with a wellsite reference to ensure that no drift has occurred since the last master calibration. At the end of the survey, sensor readings are verified again in the after-survey calibration.
The fluid resistivity measurement is calibrated to produce two straight- line transforms. One line covers the range 0.03 ohm.m to 0.33 ohm.m and the other is for 0.33 ohm.m to 3.30 ohm.m.
The CQG* crystal quartz gauge used some MRDP versions should be recalibrated when the gauge has been used in the field for 12 months or when the shift of the atmospheric pressure reading at 95 degF [35 degC] exceeds 2 psi. The time between master calibrations should not exceed 18 months.
The strain gauge should be recalibrated after it has been used in the field for 6 months or when the shift in the atmospheric pressure at 95 degF [35 degC] exceeds 0.05% full scale (e.g., 5 psi for a 10,000-psi gauge). The dead-weight tester used to calibrate strain gauges should be calibrated once every 2 years.
The strain gauge temperature calibration is a two-point linear calibration using precision resistors with reference values equivalent to 32 degF and 350 degF [0 degC and 177 degC].
Specifications
Mechanical Specifications
Temperature rating 392 degF [200 degC]
Pressure rating 20,000 psi [138 MPa]
Borehole size—min. 75⁄8 in [19.37 cm] Borehole size—max. 131⁄4 in [33.65 cm] Outside diameter 6 in [15.24 cm] Length 6.75 ft [2.06 m] MRDP-BA, MRDP-BB, MRDP-BC, and MRDP-BX: 8.6 ft [2.62 m] Weight 298 lbm [135 kg] Tension† 160,000 lbf [711,710 N] Compression† 85,000 lbf [378,100 N] H2S service Yes
† At 15,000 psi [103 MPa] and 320 degF [160 degC]. These ratings apply to all MDT modules except the Dual-Packer Module (MRPA). The compressive load is a function of temperature and pressure.
Log Quality Control Reference Manual MDT Dual-Probe Module 168
Tool quality control
Standard curves
The MRDP standard curves are listed in Table 1.
Operation
The MRPS is always run with the MRDP. The MDT tool is anchored to the formation during pressure measurements or sampling.
Standoffs should be used to minimize sticking.
Formats
The format in Fig. 1 includes all the pressures and temperatures from the different gauges. It also includes data from the MRPS.
• Track 1
– BFR1 is the fluid resistivity measured in the flowline.
– The B1TR and B1TV temperatures are measured at the resistivity cell and strain gauge, respectively.
– BSG1 from the MRPS is presented on an expanded scale as a curve and in alphanumerical values.
• Time track
– ETIM is the elapsed time at the station.
– HMS1 is the motor speed, which shows when the hydraulic motor is running to take a pretest or to set or retract the tool.
• Track 2
– DSP1 is presented as alphanumerical values and at reduced scale to help look for stabilization.
– DFR1 is shown as alphanumerical values. – D1TR and D1TS are used for fluid interpretation. • Track 3
– DHP1 is presented in alphanumerical values and at reduced scale. D1TH is a curve. Both are observed for stabilization. Table 1. MRDP Standard Curves†
Output Mnemonic Output Name
DFRi Dual-probe i flowline resistivity at sink probe DHPi Dual-probe i strain gauge pressure at
horizontal probe
DiTH Dual-probe i strain gauge temperature at horizontal probe
DiTR Dual-probe i flowline resistivity temperature at sink probe
DiTS Dual-probe i strain gauge temperature at sink probe
DQPi Dual-probe i quartz gauge pressure at horizontal probe
DQTi Dual-probe i quartz gauge temperature
DSPi Dual-probe i strain gauge pressure at sink probe † Variable i is the module number (1 to 3).
Log Quality Control Reference Manual MDT Dual-Probe Module 169
Response in known conditions
• The MRDP is used specifically to test for communication of different points of the formation with real-time acquisition. Quality control is limited to the acquired data with no noise and by ensuring that communication is noted on the observation probes, as evidenced by pressure disturbance.
• The hydrostatic pressures should be stable and plot a mud gradient close to the actual well mud gradient. The mud system should be stable for close agreement.
• The well fluid level should be known and taken into account along with deviation for comparing the measured hydrostatic pressure with the anticipated mud pressure.
• Formation pressures are usually recorded until the measured pressure is changing by less than 1 psi/min for strain gauges or less than 0.1 psi/min for quartz gauges. Pressure stabilization is critical for accurately measuring formation pressure.
• Typically there are three types of pretests:
– Normal pretest: The last-read buildup is a stabilized value that equals the formation pressure.
– Dry test: The fluid mobility is very low and there is not enough contribution from the formation to transmit the formation pressure to the flowline and pressure gauges.
– Lost seal: The pressure at the end of the set cycle is higher than the pressure at the beginning of the set cycle.
513 2.66 522 50.5 36.7 2.68 531 48.0 36.6 2.72 540 43.6 36.6 2.56 549 38.1 36.6 2.33 32.6 36.7 504 2.64 52.5 36.8 MRHY 1 Motor Speed (HMS1) (RPM) 0 8000 MRPS 1 Strain Gauge Pressure (BSG1) (PSIG) 0 10
MRDP 1 Sink Strain Gauge Temperature (D1TS)
(DEGF) 150
0 0 1
MRDP 1 Horizontal Strain Gauge Temperature (D1TH) (DEGF) 150 0 0 1 MRPS 1 Strain Gauge Pressure (BSG1) (PSIG) 549 2.33 32.6 36.7 MRHY 1 Motor MRPS 1 Strain MRDP 1 Horizontal Strain Gauge Pressure (DHP1) (PSIG) 0 10
MRPS 1 Strain Gauge Temperature (B1TV)
(DEGF) 150
0 0 1
MRDP 1 Sink Strain Gauge Temperature MRDP 1 Horizontal Strain Gauge MRDP 1 Flowline Fluid Resistivity
(DFR1) (OHMM) 1 0 Elapsed Time (ETIM) (S) MRPS 1 Strain MRDP 1 Horizontal Strain Gauge Pressure (DHP1) (PSIG) (PSIG) 0 10000 MRDP 1 Horizontal MRPS 1 Strain Gauge Temperature
MRPS 1 Flowline Fluid Resistivity (BFR1)
(OHMM) 1
0
MRDP 1 Flowline Fluid Resistivity
(DEGF) 150
0 0 1
MRDP 1 Resistivity Cell Temperature (D1TR) (DEGF) 150 0 0 1 Elapsed (DSP1) (PSIG) MRDP 1 Horizontal MRDP 1 Sink Strain Gauge Pressure (DSP1) (PSIG) 0 10000
MRPS 1 Resistivity Cell Temperature (B1TR) (DEGF) 150 0 0 1 MRDP 1 Sink Strain Gauge Pressure (DSP1) (PSIG) PIP SUMMARY Time Mark Every 60 S
PIP SUMMARY
Log Quality Control Reference Manual MDT Pumpout Module 170
Overview
The Pumpout Module (MRPO) of the MDT* modular formation dynam- ics tester is used to flow fluids from the reservoir at a controlled flowing pressure. Pressure control is required to avoid the separation of phases (i.e., gas or solids separating from oil, or liquid condensing from gas). Representative fluid samples require a “single-phase” fluid. The LFA* Live Fluid Analyzer, CFA* Composition Fluid Analyzer, or both modules can be used in combination with the MRPO to detect phase separation. The LFA module also measures the level of filtrate contamination. The fluid is then diverted to a sample chamber, where it is preserved for later analysis.
The Pumpout Module is used for the following applications:
• to pump formation fluids from the inlet port, probe, or dual packers out to the borehole before sampling
• to conduct low-shock sampling, in which fluids flow from the flow- line into sample chambers set up with hydrostatic pressure on the back side of the sample piston • to inflate dual-packer elements with borehole fluid • to pump fluid from the flowline into the formation (e.g., stress test, injection test).
Specifications
Mechanical Specifications MRPOTemperature rating 392 degF [200 degC] Pressure rating† 20,000 psi [138 MPa] Borehole size—min. 55⁄8 in [14.29 cm] Borehole size—max. 22 in [55.88 cm] Outside diameter 4.75 in [12.07 cm] Length 10.63 ft [3.24 m] Weight 340 lbm [154 kg] Tension‡ 160,000 lbf [711,710 N] Compression‡ 85,000 lbf [378,100 N] H2S Service Yes
† 25,000-psi [172-MPa] and 30,000-psi [207-MPa] versions are available upon request.
‡ At 15,000 psi [103 MPa] and 320 degF [160 degC]. These ratings apply to all MDT modules except the Dual-Packer Module (MPRA). The compressive load is a function of temperature and pressure.
Tool quality control
Standard curves
The MRPO has four standard curves (Table 1). Table 1. Standard Curves of the MDT Pumpout Module
Output Mnemonic Output Name
POS3 MRPO solenoid 3 status
POMS MRPO motor speed
POHP MRPO hydraulic pressure
POPV MRPO pump volume