Original Paper - Production Engineering
Inversion method for effective drainage volume of tight oil horizontal wells with volume fracturing based on production analysis
Authors: Meng Cai, Wei Wang, Xianjun Wang, Cuilong Kong, Minghui Zhang, Lei Wang
This study aims to accurately determine the effective drainage volume (EDV) in tight oil reservoirs, which is critical for optimizing development strategies and fracture treatment designs in China's tight oil reservoirs. The work addresses the key challenge that a significant portion of the stimulated reservoir volume (SRV) does not contribute to production, necessitating reliable methods to evaluate the actual productive volume. A rate transient analysis (RTA) model for horizontal wells with volume fracturing was developed based on material balance principles, incorporating stress sensitivity and coupled oil-water flow mechanisms within the effective stimulated reservoir volume (ESRV). The study established a flow-material balance coupling equation for the ESRV, typical type curves for volume fracturing RTA, and an analytical method for ESRV calculation. The model was applied to assess ESRV in two case wells (M2-1 and P2-1) using production data. Analysis results revealed that the ESRV constitutes only 40–60% of the total micro-seismic interpreted SRV, the developed RTA model provides an efficient and accurate method for EDV quantification, and the type curves and analytical approach effectively characterize the productive fracture network. This research presents the first integrated RTA model incorporating stress sensitivity and multi-phase flow for tight oil EDV evaluation, a practical methodology to distinguish productive ESRV from total SRV using production data, and quantitative evidence of the significant discrepancy between SRV and actual drainage volume. The findings provide crucial guidance for optimizing fracture treatments and development strategies in China's challenging tight oil reservoirs.
Executive Impact
Revolutionizing Tight Oil Production Efficiency
In tight oil reservoirs, a significant portion of the Stimulated Reservoir Volume (SRV) often fails to contribute to production. Our advanced Rate Transient Analysis (RTA) model precisely quantifies the *effective* drainage volume (ESRV), distinguishing productive zones from inert ones. This innovation leads to more accurate planning, optimized fracture treatments, and substantial economic benefits.
50%
Productive SRV Contribution
2.76%
Model Deviation (ESRV)
17%
Fracture Conductivity Impact on ESRV
Deep Analysis & Enterprise Applications
Select a topic to dive deeper, then explore the specific findings from the research, rebuilt as interactive, enterprise-focused modules.
Production Engineering Insights
This research introduces a novel Rate Transient Analysis (RTA) model specifically for tight oil horizontal wells with volume fracturing. It integrates stress sensitivity and coupled oil-water flow mechanisms, providing a more accurate evaluation of effective drainage volume (EDV) than traditional methods. The developed flow-material balance coupling equation and typical type curves offer a practical and efficient approach for field engineers to quantify productive fracture networks and optimize production strategies.
Reservoir Simulation Insights
The study leveraged numerical simulation (GEM simulator) to validate the RTA model. By establishing a conceptual tight oil production model with a preset ESRV and simulating production performance, the RTA-derived ESRV was compared against the designed value. This validation process confirmed the model's robustness and accuracy, showing a low deviation of 2.76%, and highlighted the importance of distinguishing productive ESRV from total SRV.
Fracturing Optimization Insights
A key finding is the significant discrepancy between the micro-seismic interpreted Stimulated Reservoir Volume (SRV) and the actual Effective Stimulated Reservoir Volume (ESRV) that contributes to production. Only 40-60% of the SRV was found to be productive. This insight is critical for optimizing fracture treatment designs, ensuring proppant placement creates truly effective flow paths, and avoiding unproductive stimulation efforts, leading to more efficient resource utilization.
Significant Discrepancy in Productive Volume
40-60% of micro-seismic interpreted SRV constitutes actual productive volume (ESRV)This research provides quantitative evidence of the significant difference between the total stimulated reservoir volume (SRV) identified by microseismic monitoring and the actual effective stimulated reservoir volume (ESRV) that contributes to production.
Enterprise Process Flow: Methodology Flowchart for Seepage Model Construction
Basic material balance relationship
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Mass balance equation considering compressibility of rock and fluid during pressure drop
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Simplified mass balance equation for oil-water two-phase volume
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Define comprehensive compressibility coefficient and formation condition liquid production
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Effective transformation of mass balance equation in volume
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Coupled with seepage equation considering reservoir stress sensitivity
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Mathematical model of seepage in fracturing flowback stage
| Parameter | RTA (Proposed Model) | Numerical Simulation (Designed Value) |
|---|---|---|
| Calculated ESRV | 987.6 × 10^4 m³ | 1015 × 10^4 m³ |
| Deviation | 2.76% | — |
Field Application: ESRV Quantification in Tight Oil Wells
The RTA model was successfully applied to two real-world tight oil wells, demonstrating its practical utility in quantifying productive volumes and highlighting discrepancies with microseismic interpretations.
Well M2-1
Application of the RTA model to Well M2-1 revealed that the effective drainage volume is significantly less than the microseismically interpreted SRV.
- Calculated ESRV: 380.5 × 10^4 m³
- Microseismic SRV: 923.3 × 10^4 m³
- ESRV as % of SRV: 41.2%
Well P2-1
Similar findings for Well P2-1 confirmed the consistent discrepancy between productive and total stimulated volumes.
- Calculated ESRV: 334.6 × 10^4 m³
- Microseismic SRV: 706.9 × 10^4 m³
- ESRV as % of SRV: 47.3%
Quantify Your Operational Efficiency Gains
Understand the potential time and cost savings by accurately identifying effective drainage volumes and optimizing fracture treatments with advanced AI-driven analysis.
Projected Annual Savings
$0
Hours Reclaimed Annually
0
Your Path to Optimized Production
Our structured implementation timeline ensures a seamless integration of advanced RTA methodologies into your existing workflows, delivering rapid and measurable improvements.
Phase 1: Data Integration & Model Setup
Aggregate historical production data, reservoir characteristics, and microseismic interpretations. Configure the RTA model with stress sensitivity and multiphase flow parameters specific to your tight oil reservoirs.
Phase 2: ESRV Calculation & Validation
Apply the developed analytical and type-curve methods to calculate ESRV from flowback data. Validate results against existing stimulated volume estimates and calibrate the model for local geological conditions.
Phase 3: Fracture Treatment Optimization & Strategy Refinement
Utilize ESRV insights to refine fracture treatment designs, well spacing, and overall development strategies. Focus on maximizing productive volume while minimizing unproductive stimulation. Integrate with surface facilities for holistic optimization.
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