Novel Well Test Design for the Evaluation of Complete Well Permeability and Productivity for CSG Wells in the Surat Basin

Abstract

The Surat Basin Coal Seam Gas (CSG) play requires a vast number of wells to develop, and reservoir productivity changes quickly over small distances. Well testing provides a means to evaluate these changes. But, the high cost of conventional testing precludes sufficient tests to ensure areal and statistical coverage across a large well stock. This paper discusses a new approach whose reduced cost allows five times more wells to be tested than conventional methods. By testing more wells, there is more data for subsurface model calibration and productivity fairways can be better mapped and developed.In the Surat Basin CSG play there is an industry-wide completion technique that uses air to lift every well to size the initial downhole pump for dewatering. This paper describes an enhancement to this standard pump sizing test which facilitates the provision of key reservoir information: full well permeability, skin and productivity. This novel well test is termed an Air Assisted Flow Test (AAFT).During the AAFT the well is produced at a predictable drawdown for up to an hour whilst accurate rate measurements are made at surface. A downhole shut-in is then performed and a pressure gauge measures the build-up pressure response. The additional equipment and rig time have been designed to add a minimal cost to the standard completion operation and test cost is 20% of a traditional Drill Stem Test (DST).Field tests using the AAFT and multiple dual packer DST's in the same well clearly demonstrate that both testing methodologies deliver the same results. It is therefore valid to incorporate the AAFT into the extensive permeability database for the Surat Basin. Additionally drawdown dependent skin has been observed in data from the new AAFT. This phenomenon is interpreted to be the result of stress dependent coal fracture permeability in the near well bore region.This new testing method is only directly relevant to CSG developments. However the awareness to gather additional data, from enhancing a standard operation, is applicable to all unconventional and conventional reservoirs.

Developing synthetic reservoir type curve model for use in evaluating surface facility and gathering pipe network designs

“…Fisk et al (2010) report that in the Bowen Basin of Queensland, it is not unusual for production to changes as much as 50-75 % between neighbouring wells within a few M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 kilometres. Likewise for the Surat Basin of Queensland, where reservoir productivity changes quickly over small distances (Bottomley, et al, 2015).…”

Transient pressure analysis for vertical oil exploration wells: a case of Moga field

“…There is no single method of testing and sampling, that is, the best for the purpose under every circumstance (Soh 2010;Whittle et al 2003). The selection of the test type, sequence and duration has to be balanced against operational risk, geology, environmental constraints, equipment and the economic value derived from affecting early decisions on project appraisal or development (Bottomley et al 2015;Li et al 2014).…”

Оценка Информативности Определения Фильтрационных Параметров Пласта На Основе Интерпретации Кривых Стабилизации Давления

“…Еще одним инструментом, который может слу жить для определения параметров пласта, являет ся метод анализа добычи (АД), который реализо ван в программном комплексе KAPPA Worksta tion v5.20.01 модуль Topaz. Стоить отметить, что для получения качественных данных необходимы данные длительного мониторинга работы скважи ны -в течение нескольких месяцев, желательно с момента ввода ее в эксплуатацию [19][20][21][22]. Преиму ществом обработки данных в Topaz является то, что получение фильтрационно емкостных параме тров пласта не требует дополнительных исследова ний и, как следствие, сокращаются потери добычи и не требуется дополнительных экономических вложений.…”