Integrated Production Modelling of Gas Wells in the Northern Cooper Basin with Brief Studies on Alternative Methods of Estimatimg Bottom-Hole Static Pressure
Engineering Honours Degree 2007
University of Adelaide
Integrated production modelling is essential for well performance evaluation and enhancement of the production system. It is a process of predicting the effects of changes through a systematic analysis of individual components and the impact of their interaction on field performance (Bikoro, 2005).
The inflow performance relationship (IPR) of wells is required in production well modelling and optimisation. For this, the bottom-hole pressure needs to be known, either by actual measurement or by calculation from wellhead pressure measurements (Smith et al., 1992). Bottom-hole pressure measurements are often impractical (Lee and Wattenbarger, 1996). They are costly and require the reservoir to be shut-in long enough for the reservoir pressure to stabilize.
The project was essentially split into two components. The major component was developing and running an integrated production model of the Patchawarra South West region in the Northern Cooper Basin using GAP, PROSPER and MBAL software. The objectives were to study well inflow performance of stacked sand systems and optimise gas production through debottlenecking opportunities and additional drill projects. Debottlenecking refers to the process of increasing the production capacity of existing facilities through the modification of existing equipment to remove throughput restrictions (ConocoPhillips, 2007).
A minor component of the project was to investigate different methods of estimating bottom-hole static pressure (BHSP) using data from wells in the same region with the aim of finding alternative methods compared to conventional static gradient surveys (SGS).
Integrated production modelling provides an effective understanding of wells and field performance. Following four optimisation scenarios were investigated:
(1) Effect of switching flowline for a high rate well
(2) Effect of connecting a tie-in to different satellite (debottleneck)
(3) Effect of two additional drill projects
(4) Effect of debottleneck with additional drill projects.
The integrated production modelling found that there was a great, immediate improvement possible by flowing Well G1 (a high gas rate producer) directly to the compressor at the satellite. Currently this well is being flowed along flowlines tie-ing into other fields in the region. Switching this flowline may provide a rate increase of 3.4 MMscf/d. A debottleneck opportunity was investigated and it was found that this option may provide a rate increase of 4.0 MMscf/d and a reserves increase of 2.5 Bcf. These results do not include backout through the flowline, but did include compression along the flowline. The expected backout, which refers to the loss or deferment of gas production, should be quantified to assess fully if the project is likely to be economically viable. However, it should be noted that the volume change relief for the compressor at the satellite due to debottenecking, will allow for further development of fields in the Patchawarra South West region. The impact of new development drill projects on the total incremental gas rate was dependent on whether to run the debottleneck or not.