On June 24, PetroChina Xinjiang Oilfield announced that Wantan 101H, an ultra-deep tight gas horizontal well in the Mosuowan exploration area and the deepest plug-and-perf horizontal well in Xinjiang Oilfield, had successfully completed all 15 stages of fracturing operations. The project set multiple new engineering records for ultra-deep wells and plug-and-perf horizontal well fracturing in Xinjiang Oilfield, marking a solid step forward in ultra-deep reservoir stimulation. The well has now been opened and is in the flowback and oil testing stage.

In underground oil and gas reservoirs, rocks are tight and pores are extremely small, making it difficult for crude oil or natural gas to flow into the wellbore on their own. Fracturing artificially creates a large number of fracture channels in the formation, greatly improving oil and gas flow paths, enabling smoother production and enhancing single-well output and recovery. The fracturing process uses high-pressure pumps to inject fracturing fluid into the formation, forcibly opening fractures in the rock and filling them with proppant to form high-permeability flow channels in the reservoir. Plug-and-perf, or bridge plug perforation, is a key technology for staged fracturing in horizontal wells. A bridge plug and perforating gun are run into the well by cable; the bridge plug is first set to isolate the target section, and then the perforating gun is detonated to create holes in the casing, establishing channels for fracturing fluid to enter the formation. Isolation and perforation are completed in a single trip.

Wantan 101H is Xinjiang Oilfield’s first ultra-deep plug-and-perf horizontal well. It was drilled to a vertical depth of 7,470 meters and a measured depth of 8,226 meters, far deeper than conventional tight gas wells, facing extreme conditions of ultra-deep depth, ultra-high temperature and ultra-high pressure.

The exploration division and engineering technology department of Xinjiang Oilfield organized multiple rounds of program review, repeatedly evaluating deep tight gas stimulation concepts, material selection, parameter optimization and construction safety measures. Contingency plans were formulated item by item for wellbore integrity, pressure control, sand plugging risks, downhole tool running and retrieval, and other key issues. The program underwent multiple rounds of iteration and improvement to ensure safe and smooth operations.

The successful fracturing operation at Wantan 101H represents an important breakthrough in ultra-deep reservoir stimulation for Xinjiang Oilfield. It has accumulated valuable field experience for future ultra-deep horizontal well fracturing operations and formed a replicable and scalable technical solution and construction organization model, giving it important demonstration significance.

Further Analysis:

1. Breaking through the limits of “three ultra” conditions

In an extreme environment with a vertical depth of more than 7,400 meters and a measured depth of more than 8,200 meters, bottomhole temperatures usually exceed 150°C and formation pressure coefficients are extremely high. Under such high-temperature and high-pressure conditions, electronic components in conventional fracturing equipment are prone to failure, fracturing fluid viscosity declines rapidly, and the difficulty of transporting proppant rises exponentially.

However, Xinjiang Oilfield’s operation was not simply a matter of using higher-specification equipment. Instead, targeted research and development was carried out in areas such as the fracturing fluid system and plug-and-perf tools. The successful completion of 15 fracturing stages proves that Xinjiang Oilfield has mastered pressure-control technology for the effective expansion of fracture networks in ultra-deep reservoirs, addressing not only the challenge of opening fractures, but also the challenge of keeping them propped open.

1. Major strategic significance for the economic development of tight gas

In ultra-deep wells, the cost of well construction rises sharply with every additional 1,000 meters of vertical depth. In the past, many ultra-deep tight gas resources were regarded as a “hard nut to crack,” with the key question being whether single-well production could justify the high engineering investment.

After this well successfully established high-conductivity flow channels, if oil testing delivers high-yield gas flow, it will be highly significant for the economic evaluation model of the Mosuowan exploration area in the Junggar Basin. It would show that ultra-deep tight gas is no longer merely a figure in geological reserves, but can be converted into real, producible output.