No abstract

During the past five years, shale gas developments have changed the game for the US natural gas industry. Globally, shale exploration activities are also increasing. China is in the early stages of exploiting the world's largest reserves of shale gas resources while attempting to cope with increasing energy demands.This paper presents a case history of applicable technology currently used in North America for initial attempts at shale gas exploration in China. This case study is the first Cambrian age marine shale well in the Qiongzhusi formation located in the shale-gas-rich Sichuan province.Many technologies were brought from North American shale gas applications for this well (Chong et al. 2010). This study describes the technologies used to drill and complete the targeted shale gas formation and guide the completion and stimulation design. The target formation was drilled horizontally and the casing was cemented. The formation was then stimulated with multiple stages after full integration of data from geologic, geomechanical, petrophysical, and core analysis, which aided in the fluid and proppant selection, proppant concentration, and the designed injection rate. A diagnostic fracture injection test (DFIT) was performed before the main treatment to confirm fracture gradient, closure, pore pressure, system permeability, and leakoff. Microseismic mapping was also used, which proved to be valuable when planning and assessing the fracturing results.Currently, the well is flowing gas at rates comparable to early production time in a typical North American shale gas well with a similar type of completion.This case study serves as an example of successful implementation of proven technology outside of the North America shale gas market. Continued projects such as this one are the predecessor to full-scale development of shale gas and have helped shape the abundant gas supply currently in the United States. Additionally, these types of projects are necessary to help China improve their future outlook on gas supply.

During the past five years, shale gas developments have changed the game for the US natural gas industry. Globally, shale exploration activities are also increasing. China is in the early stages of exploiting the world's largest reserves of shale gas resources while attempting to cope with increasing energy demands. This paper presents a case history of applicable technology currently used in North America for initial attempts at shale gas exploration in China. This case study is the first Cambrian age marine shale well in the Qiongzhusi formation located in the shale-gas-rich Sichuan province. Many technologies were brought from North American shale gas applications for this well (Chong et al. 2010). This study describes the technologies used to drill and complete the targeted shale gas formation and guide the completion and stimulation design. The target formation was drilled horizontally and the casing was cemented. The formation was then stimulated with multiple stages after full integration of data from geologic, geomechanical, petrophysical, and core analysis, which aided in the fluid and proppant selection, proppant concentration, and the designed injection rate. A diagnostic fracture injection test (DFIT) was performed before the main treatment to confirm fracture gradient, closure, pore pressure, system permeability, and leakoff. Microseismic mapping was also used, which proved to be valuable when planning and assessing the fracturing results. Currently, the well is flowing gas at rates comparable to early production time in a typical North American shale gas well with a similar type of completion. This case study serves as an example of successful implementation of proven technology outside of the North America shale gas market. Continued projects such as this one are the predecessor to full-scale development of shale gas and have helped shape the abundant gas supply currently in the United States. Additionally, these types of projects are necessary to help China improve their future outlook on gas supply.

China has surpassed the US to become the largest energy consumer in the world, and it is projected that China's demand for energy will increase from 97 quadrillion Btus in 2010 to 142 quadrillion by 2040 (ExxonMobil 2013), a 46% increase. EIA estimated China has 1,115 Tcf of risked technically recoverable shale gas resources (EIA 2013), making it an important resource for China's future energy demand. Currently, the majority of China's shale gas exploration and development are focused on three marine shales in and around Sichuan basin: the Silurian Longmaxi, the Cambrian age Qiongzhusi, and Niutitang. Of these, it is estimated that the Longmaxi has the highest risked recoverable shale gas (EIA 2013). However, because of its complex paleo tectonic movement, the Longmaxi formation is a highly fractured and faulted system, which makes it challenging to drill and fracture. This paper is a case study of operational challenges encountered when fracturing the Longmaxi formation. A brief geological review of Sichuan basin geology is discussed to present the origin of the geological complexity. The diagnostic fracture injection test (DFIT), hydraulic fracture job charts, log analysis, and microseismic data during fracture stimulation of a horizontal Longmaxi well is analyzed as an example to show the difficulty operators could experience when fracturing a shale formation developed in such a complex geological environment. Possible solutions are discussed as lesson learnt. The production is also detailed.