China has seen its natural gas consumption rise significantly over recent years. As a result, unconventional energy, specifically shale gas, has become a focused alternative. However, major challenges to develop efficient shale gas extraction, such as the geology, undulating terrain, lack of water resources, immature expertise prevail. Thus, large scale commercial production of shale gas remains in its infancy.
The Sichuan basin is a testament of this where exploration and production of unconventional reservoirs have taken place since the 1950s. With the basin resting in a major compressional tectonic area, part of the shale gas reservoirs is fractured, sensitive to abrupt structural dip changes and faulted standoffs. This complicates reservoir stimulation with unpredictable fracture orientations and growth. Lateral property changes within the reservoir and varying stratigraphic thickness adds to this shortcoming.
To shorten the learning curve, successful and established workflows from US plays such as the Eagle Ford, Marcellus and Barnett were introduced. From these plays, it was established that different shale plays retains distinct differences that were addressed through customization in the process and workflows. The differences were identified through detailed evaluations of reservoir quality(RQ) and completion quality(CQ). However, to address the local challenges during well construction, a new focus is needed with the introduction of drilling quality (DQ).
In this aspect, PetroChina South West Oil and Gas Company (SWOGC) operating in one of the Sichuan shale plays adopted the above workflow to accumulate and analyze the data with the objective to establish the main drivers for reservoir production towards recovery enhancement. Consequently, the customization of process and workflows to support large scale commercial shale gas development in the Sichuan Basin can be achieved.