Introduction
In the dynamic landscape of oil production, lift gas optimization emerges as a pivotal strategy for enhancing gas-lifted wells’ productivity and financial performance. This technique focuses on fine-tuning gas lift injection rates and optimally allocating lift gas to wells based on profitability and operational efficiency. By considering factors such as well composition, ownership, and financial implications, lift gas optimization ensures an effective distribution of resources, while continuous monitoring of gas lift compressors aids in managing compressor load, preventing compressor failures and unplanned shutdowns.
Understanding Gas Lift Injection
Gas lift injection involves injecting compressed natural gas into oil wells through specialized downhole valves. This method leverages gas bubble buoyancy to decrease oil density within the production tubing, facilitating the upward movement of hydrocarbon fluids by leveraging the buoyancy provided by gas bubbles. However, it’s essential to manage the gas injection carefully; over-injection can lead to reduced production, increased operational pressures, and the undesirable “foaming” of the lift gas within the production liquid.
Deciphering the “Lift Curve”
A cornerstone concept in gas lift operations is the “Lift Curve,” which represents the relationship between the production rate of a well and the amount of lift gas injected. Characterized by its non-linear nature, the curve reveals how production rates initially increase with gas injection up to a peak point, beyond which further injection leads to a decline in output. This curve is more accurately described as a “Lift Surface” because it is influenced by various factors, including operating temperatures, wellhead pressure, and reservoir pressure, making peak production a moving target on this multidimensional landscape.
The Essence of Gas Lift Optimization
Lift gas optimization aims to allocate available gas judiciously, maximize production, reduce operational costs, and meet business objectives while navigating through operational constraints such as compressor capabilities, water production, and the overall downstream production rate capacity. This process enhances production from mature fields and optimizes the economic return and lift gas allocation, incorporating advanced analytics for comprehensive production operation insights.
Benefits of Optimization
Lift gas optimization offers numerous advantages, including:
- Significant production increases, with typical gains of around 15% on a field-wide basis.
- Extended operational lifespan of fields, reducing costs and health, safety, and environmental (HSE) risks.
- Optimized economic returns and gas allocation.
- Enhanced compressor monitoring and multi-phase virtual metering at various production levels.
Optimization Process Overview
The optimization process begins with the digitalization of well and production data, followed by the execution of multi-rate tests to understand the wells’ performance under varying conditions. This data enables the creation of models representing each well’s gas lift performance curve. With these models, constraints such as available lift gas and compressor limitations are considered to optimize gas allocation. This optimization can be executed for individual wells through Model Predictive Control (MPC) or applied across multiple wells by adjusting total gas allocation to meet overall asset constraints.
Conclusion
Lift gas optimization is a useful tool for achieving optimal gas injection rates and maximizing liquid production while adhering to necessary operational constraints. Whether focusing on individual wells or entire assets, this approach offers a pathway to improved production efficiency and financial performance. We invite further discussion on how lift gas optimization can be tailored to enhance your production operations, ensuring you achieve your production targets efficiently and effectively.
