ZITN High-Precision Distributed Optical Fiber Acoustic Sensing (DAS) System is a new type of sensing technology that enables continuous distributed detection of vibration and acoustic fields. ZITN High-Precision Distributed Temperature Sensing (DTS) utilizes the characteristic that coherent Rayleigh scattering, excited by a narrow-linewidth single-frequency laser in an optical fiber, is highly sensitive to strain. Combined with the principle of time-domain reflectometry, it performs real-time dynamic monitoring of tiny changes caused by vibration and acoustic field information in the environment around the optical fiber. This enables it to feed back acoustic field information and vibration changes along the optical fiber path, providing an efficient, sensitive, and reliable testing method for applications such as oil well logging and pipeline monitoring.
Specification Parameters
|
Model |
High-Precision Distributed Optical Fiber Acoustic Sensing (DAS) System ZTDAS-5000 Series |
|
Optical Fiber Type |
9/125μm Single-Mode Optical Fiber |
|
Spatial Resolution |
≤1m |
|
Minimum Sampling Interval |
0.1m |
|
Measurement Distance |
≥10km |
|
Frequency Response Range |
0.1Hz-20kHz (related to distance measurement) |
|
Storage Capacity |
≥1T |
Application
|
Category |
Included Well Types |
Core Logging Challenges |
DAS Solutions |
|
Conventional Production |
High-yield Flowing Oil Wells, Rod Pump Wells |
Temperature pulse (flowing wells); Phase monitoring & production layer depletion assessment (flowing wells); Equipment interference & difficult dynamic monitoring (rod pump wells) |
1. Pump Condition Diagnosis |
|
Unconventional Gas (Coalbed Methane) |
CBM Drainage Wells, CBM Horizontal Wells |
Drainage & gas production monitoring, heterogeneity, long horizontal sections; Fracturing evaluation, rod pump interference |
1. Gas-Water Profiling & Horizontal Section Evaluation 2. Fracturing Monitoring & Pump Diagnosis |
|
Unconventional Gas (Shale/Tight) |
Shale Gas Horizontal Wells, Natural Gas Horizontal Wells, Complex Natural Gas Wells |
Ultra-long horizontal section production profile, multi-stage fracturing evaluation; Phase multiphase flow, wellbore interference, flowback monitoring |
1. Real-Time Fracturing Evaluation (Core) |
|
Injection Wells |
Water Injection Wells, CO₂ Injection Wells, N₂ Injection Wells |
Injection profile, fluid front channeling, phase change (CO₂), corrosion, leakage |
1. Injection Point Verification & Leak Detection 2. Injection/Production Profiling |
|
Gas Storage Injection-Production Wells |
Gas Storage Injection-Production Wells |
Bidirectional injection-production profile, caprock tightness, storage capacity dynamics, wellbore integrity, gas-water interface, strain stress |
1. Early Caprock Leak Monitoring (Critical) |
Product Features
- Supports RAW/HDF5 raw/phase data.
- Supports LAS/CSV format FBE report data.
- Features long-term real-time FBE analysis and display functions.
- Offers excellent low-frequency vibration response of 0.1Hz-1Hz.
- Supports 10Gbps 10 Gigabit Ethernet port disk array, enabling long-term continuous data acquisition.
Case study
Overview
Well XX, a horizontal well in the Southwest Oil & Gas Field, exhibited abnormal gas logging after cementing of the fourth section. Gas flow at the wellhead reached 0–92 m³/h, suggesting potential casing coupling leakage. On May 12, 2022, optical fiber was deployed through drill pipe to 4500 m for combined DTS + DAS testing.
Challenges
High mud weight and minimal leakage, below the detection threshold of distributed fiber sensing.
High downhole pressure caused existing sealing methods to fail, and cable surge during retrieval led to fiber breakage at the tool joint.
Reducing mud density introduced well control risks, with no suitable cable hanger available for tubing.
Lack of accurate cable depth correlation and effective fiber attenuation testing to confirm suspected defect points.
Solution
Using integrated DAS and DTS data, acoustic and temperature anomalies along the wellbore were analyzed to precisely locate leakage points.
Interpretation
Frequency analysis of DAS data identified channeling behind the casing between 3815–4415 m. Four leakage points were confirmed at casing couplings-specifically at depths of 3971.2 m, 4001.2 m, and two others.
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