Well Trajectory, Completion and Fracture Design Changes Improve Execution for Deep Unconventional Tight Gas Targets in the Cooper Basin, Australia
- Raymond L. Johnson (University of Queensland) | Ruizhi Zhong (University of Queensland) | Lan Nguyen (Real Energy Corporation Limited)
- Document ID
- Society of Petroleum Engineers
- SPE Hydraulic Fracturing Technology Conference and Exhibition, 5-7 February, The Woodlands, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2019. Society of Petroleum Engineers
- 5.8 Unconventional and Complex Reservoirs, 7.6.6 Artificial Intelligence, 1.12.6 Drilling Data Management and Standards, 5.8.1 Tight Gas, 1.10 Drilling Equipment, 4 Facilities Design, Construction and Operation, 1.12 Drilling Measurement, Data Acquisition and Automation, 4.1.2 Separation and Treating, 2.1.3 Completion Equipment, 3 Production and Well Operations, 5 Reservoir Desciption & Dynamics, 2.4.1 Fracture design and containment, 2 Well completion, 1.10 Drilling Equipment, 1.12.2 Logging While Drilling, 2.2.2 Perforating, 4.1 Processing Systems and Design, 2.5.2 Fracturing Materials (Fluids, Proppant), 5.1 Reservoir Characterisation, 2.4 Hydraulic Fracturing, 1.6 Drilling Operations, 3 Production and Well Operations, 2.2 Installation and Completion Operations
- Strike-slip, Cooper Basin, Completions, Hydraulic Fracturing, Tight Gas
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The Cooper Basin of Australia is challenged by strike-slip to reverse stress regimes, adversely affecting hydraulic fracturing treatments. In drilling, the high deviatory stress conditions increase borehole breakout, affect log acquisition and impact cementing job quality. The non-favourable stress conditions in conjunction with natural fracturing result in: complex fracturing (with shear and sub-vertical components); high near-wellbore pressure loss (NWBPL) values; and stimulation of lower permeability, low modulus intervals (e.g., carbonaceous shales, interbedded coals) in preference to the targeted and higher modulus, tight-gas sandstones. Typically, vertical wells have been employed in past completions of the Cooper Basin as well as in the offsetting areas to the case study in the Windorah Trough, Southwest Queensland.
We will present the results from two case study wells offsetting a previous vertical well where well trajectory, completion and fracture design changes were employed in an ongoing experiment to improve job execution for Patchawarra tight gas reservoir treatments in the Cooper Basin. The two wells were directionally deviated at 31° and 25° final inclinations from vertical with azimuth <10 deg from the maximum horizontal stress direction, as determined from offsetting well data. To better define sections with limited, poor or missing log data (because of difficult hole conditions), drilling data, logging while drilling (LWD) gamma ray data, openhole conventional and dipole sonic logs, along with prior 1D stress data were used with a machine learning model to improve stress profiling and reservoir characterization. Next, perforations were shot 0 and 180° phased along the wellbore and initial fluid viscosity was increased to better align the hydraulic fracture and reduce NWBPL, respectively. Finally, diagnostic fracture injection tests (DFIT) were performed in sections of varying moduli below and in the zone of interest in order to verify the horizontal strains and calibrate the final 1D stress profile prior to stimulating both wells.
The improved well and perforation alignment to the maximum horizontal stress direction has improved reservoir connection, lowered NWBPL in some cases, and in some cases improved fracture containment. Decreasing injection rates and minimizing perforated intervals has improved targeting of desired intervals; however, overall fracture widths remain low and continue to be sensitive to proppant sizing and concentrations with several screen outs experienced. This experimentation has resulted in short-term production improvements in the wells using 4- and 3-stage treatments relative to the offsetting vertical well where a 5-stage treatment was executed.
|File Size||2 MB||Number of Pages||20|
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