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Compilation And Evaluation Of Production Logging And Surveillance Data For The Moomba South Field Development, Cooper Basin SA

Hubbard, Peter

Petroleum Engineering Honours Degree, 2011

University of Adelaide

Abstract

The Moomba fields are located around the Moomba processing plant in South Australia. The field has been producing gas from the Cooper Basin for 42, years having been discovered in 1966. To date there have been 161 gas wells drilled in the Moomba Fields. The field is split into two, Moomba North and Moomba South. Currently there are 76 wells drilled in the Moomba South and 85 wells drilled in Moomba North. With this large number of wells there is an abundant amount of data on the field. This project seeks to compile some of these datasets to better understand and help plan new infill potential in the Moomba South field.

The aim of this project is to provide important information for making infill field development decisions in the Moomba South field. To do this, 4 tasks were required. The first task was to providing a better understanding of the completions and production history of the fields, through a compilation of all the completion and production data.  The second was to calculate the well spacing and review the historic development of the two fields to see how the well spacing has changed over time and how this has affected the estimated ultimate recovery (EUR). The third task was to investigate production contributions from memory production logging data for two formations, the Toolachee and Daralingie. This was then used to calculate drainage circles for the respective formations and was plotted on a bubble map to show expected drainage areas. The final task was to bring all this information together with bubble maps of well spacing and drainage circles to show areas where there was potential for infill wells.

The main aim of drilling infill wells is to increase recovery from a reservoir by having more drainage points. Optimisation of infill drilling is required to determine the best possible number of wells to drill, without over drilling (uneconomic) or under drilling (leaving undrained reserves). Infill wells can either have incremental drainage resulting in increased reserves by accessing new undrained sand lenses or accelerated drainage by accessing sands that are already being depleted by neighbouring wells. In most cases it is a combination of incremental and accelerated drainage.

Using both a static and a dynamic model, a 29 well infill case was created by the asset team, which reduced the well spacing from 238 currently to 164 acres. These 29 new wells were used with the bubble maps of well spacing and drainage circles to show that 14 wells have more potential for incremental reserves, leaving 15 wells with more potential for accelerated drainage. This project ranked these wells on estimated accessible OGIP. The top 5 wells have been chosen and compared to their ranking according to EUR from the simulation model. This work has helped contribute to the 2011 reserves asset work for Santos.

Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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