An Efficient Approach for History-Matching Coal Seam Gas CSG Wells Production

Abstract

QGC's current full-field reservoir model comprises hundreds to thousands of CSG wells. This presents a considerable challenge from a history-matching standpoint compared to a conventional workflow where well-level adjustments may be made on one well at a time. In QGC, a model with an improved well-level match is desired as the resulting well forecast will enable decisions on a well-level to be made more confidently, such as the prioritization of well workovers. Previously a field-level history-match was deemed acceptable when the model was only used for field development planning. The method parameterizes the well-level relative error in simulated production from the model versus observed production. The workflow utilizes this data, known as well-level modifiers, to alter subsurface properties. This has been achieved with a semi-automated workflow to make the process efficient and repeatable, but also to enable engineering judgement to be incorporated in the history-matching process. The feedback loop is also an essential component of the workflow as it allows the well-level modifiers to be sense checked against the regional geological trends. This further encourages collaboration within a multi-disciplinary team. These well-level modifiers can also be used to create history-match metrics, which can be spatially mapped to help target specific areas for improvement in history-match quality. Some powerful use of visualization techniques discussed in this paper has not only minimized the mismatch but ensures the characteristics of the production history and geological trends are honoured to assure the robustness of the history-match and the resulting model predictability. The workflow has significantly reduced the time and efforts spent in delivering an improved well forecast when required. The technical development community in QGC has actively nurtured a culture of ideas sharing and innovation, which made the development of this workflow possible.

New Integrated History Matching Approach for Vertical Coal Seam Gas Wells in the KN Field, Surat Basin, Australia

“…Chang and Gizat in 2018 stated that it is better to incorporate the engineering judgments into the history matching process. Using this strategy, they completed the well-level matching for a gas field by adjusting the permeability, gas content, and fracture porosity …”

“…Using this strategy, they completed the well-level matching for a gas field by adjusting the permeability, gas content, and fracture porosity. 12 From the discussions mentioned above, we know that there are disputes about the history matching approach, such as the selected parameters for modifying and the principles for modifying these parameters. In this study, we focus on the MTE method.…”

Affecting Factors on History Matching Field-Level Coal Seam Gas Production from the Surat Basin, Australia

“…7 Furthermore, the demand to enable confident decision-making at the well level to help the field production such as the prioritization of workovers was addressed with an efficient approach for HM in the Surat Basin. 8 Karacan (2021) mapped the dynamic properties of Black Creek coal seams from Black Warrior Basin based on the production HM of 45 single wells and built a proxy reservoir model to explore the applicability for multiple wells' reservoir simulation. 9 Moreover, CSG reservoir simulation is regarded as one of the most effective tool to not only help model the gas content reduction during coal mining but also add value to utilizing produced methane as an energy source.…”

“…As a result, a series of HM relevance studies have been carried out in characterizing reservoir properties and optimizing field development strategies. − For instance, to accomplish quick cycle decision-making of a large number of CSG wells, Howell et al (2014) ran the HM through a simulation model of the Surat Basin Walloon subgroup and presented the guidelines to enable a quicker turnaround of reservoir model predictions . Furthermore, the demand to enable confident decision-making at the well level to help the field production such as the prioritization of workovers was addressed with an efficient approach for HM in the Surat Basin . Karacan (2021) mapped the dynamic properties of Black Creek coal seams from Black Warrior Basin based on the production HM of 45 single wells and built a proxy reservoir model to explore the applicability for multiple wells’ reservoir simulation .…”

A New Method for Numerical Simulation of Coalbed Methane Pilot Horizontal Wells—Taking the Bowen Basin C Pilot Area in Australia as an Example

“…Nevertheless, core tasks, including parameter selection, modification sequence, and adjustment magnitude, remain predominantly manual. Scholars have primarily focused on parameter adjustments to optimize matching accuracy [6,7], addressing factors such as permeability, gas content, relative permeability of water and gas, Langmuir volume (VL), Langmuir pressure (PL), and fracture porosity [8][9][10][11]. However, research on the direction and extent of parameter adjustments is somewhat limited, and the methods applied are often arbitrary.…”