According to PetroChina Dagang Oilfield Company, a breakthrough has been achieved in the Nangang Oilfield’s difficult-to-produce “low- to ultra-low-permeability” reserve project. After being put into production, eight pilot test wells have maintained stable output for more than two months, delivering daily production of 190 tonnes of oil and 190,000 cubic meters of gas, equivalent to 340 tonnes of oil and gas per day.

As the first large-scale development block to be fully constructed and brought on stream by Dagang Oilfield in nearly three years, the project is expected to add 15,000 tonnes of crude oil and more than 20 million cubic meters of natural gas within the year, successfully converting difficult-to-produce reserves into efficient production capacity.

The lower Sha-1 reservoir in Nangang Oilfield is buried at depths exceeding 4,000 meters and is characterized by poor reservoir properties, making it a typical low- to ultra-low-permeability oil reservoir. Under the traditional vertical well development model, crude oil mobility is poor: although initial single-well output can be relatively high, decline rates are rapid and investment costs are high, leaving the field long trapped in a dilemma of “reserves exist but are hard to produce.” Zhao Liang, technical lead of the Nangang Oilfield project, explained that developing such reservoirs with vertical wells is like “using a straw to drink a viscous liquid,” mobilizing only near-wellbore reserves and making long-term stable production difficult. How to effectively tap these large but long-dormant reserves became a major development challenge for Dagang Oilfield.

Confronted with tens of millions of tonnes of “visible but unproducible” reserves, Dagang Oilfield broke away from the traditional “vertical well + conventional fracturing” model and shifted its development approach. Drawing on shale oil development experience, it adopted a technology combination of “horizontal wells + volumetric fracturing + energy-enhanced huff-and-puff” in the main structural areas. Once implemented, this innovative pathway effectively built “three-dimensional flow channels” and a “power engine” for the subsurface reservoirs. Long horizontal sections precisely penetrated oil-bearing layers to maximize well–reservoir contact; volumetric fracturing created complex fracture networks through high-pressure stimulation to open oil flow pathways; and energy-enhanced huff-and-puff continuously injected动力 into crude oil flow, overcoming the bottleneck of poor mobility. Enabled by these technologies, the pilot wells achieved high output after startup, with peak stable daily oil production of 48 tonnes per well and an average of 24 tonnes per well, successfully realizing the economic development of difficult reserves.

At the same time, focusing on these large volumes of hard-to-produce reserves, the Dagang Oilfield labor union organized a campaign themed “Winning the Production Defense Battle and Securing Crude Oil Initiative,” mobilizing departments such as the Exploration Division, Engineering Technology Division, and Production Operations Division to launch an “exploration and appraisal assault.” By breaking with the conventional development model and promoting a strategy of “rethinking approaches, transforming models, and strengthening management,” the field achieved notable results.

Jiang Wenya, Manager of the Exploration Division/Geophysics Department of Dagang Oilfield Company and an ECF young expert, said that the successful practice at Nangang Oilfield not only opens a new pathway for Dagang Oilfield’s high-quality development, but also breaks the long-held notion that difficult-to-produce reserves are “off-limits,” providing replicable and scalable experience for the development of similar low-permeability reservoirs.