In 2025

PetroChina Tuha Oilfield Company proposed the exploration strategy of "exploring both deep and shallow layers for three-dimensional breakthroughs". Well Fukang2 was deployed on the eastern slope of Fukang sag

in Junggar Basin. During well testing

the Upper Permian Shangwuerhe Formation and the Lower Triassic Jiucaiyuan Formation produced high-yield industrial oil flows of 25.44 m

3

/d and 56.16 m

3

/d

respectively. This opened up a new phase of three-dimensional exploration characterized by vertical multi-strata and planar multi-fields in the study area. Based on outcrop

drilling and logging

seismic

and various analytical test data

a comprehensive study was performed on hydrocarbon sources

reservoirs

and accumulation of oil reservoir in the Shangwuerhe and Jiucaiyuan formations on the eastern slope of Fukang sag. The research results indicate that the study area primarily develops two sets of source rocks

i.e. the Permian Lucaogou Formation and the Upper Member of Carboniferous Songkaersu Formation. Their organic matters are dominated by Type Ⅱ

1

-Ⅱ

2

and Type Ⅱ

2

-Ⅲ kerogens

exhibiting good to excellent and fair to good organic richness

respectively. Both suites of source rocks are predominantly in the mature stage. The crude oil from Well Fukang2 is characterized with relatively light carbon isotopes and predominant algal-derived organic matters

whose biological precursors are formed in a saline reducing environment

consistent with the depositional conditions of the Lucaogou Formation source rocks. This suite of source rocks exhibits high hydrocarbon generation intensity

generally exceeding 200×10

4

t/km

2

. The Shangwuerhe Formation and Jiucaiyuan Formation mainly developed the braided river delta to lacustrine sedimentary systems

where the reservoirs demonstrate low porosity and ultra-low permeability. The Shangwuerhe Formation is dominated by secondary dissolution pores

residual intergranular pores

and microfractures

whereas the Jiucaiyuan Formation is primarily characterized by residual intergranular pores. Both the Shangwuerhe Formation and Jiucaiyuan Formation exhibit lithologic sandstone reservoirs. On the eastern slope of Fukan

g sag

under the control of large-scale sand bodies

nose-shaped structural settings

and overpressure-fracture systems

three favorable exploration areas

i.e.

Fuzhong

Kangtan1

and Fu47 structures with a total area of approximately 310 km

2

were identified in the Shangwuerhe Formation. Moreover

under the control of hydrocarbon migration pathways and high-quality reservoirs

two favorable exploration areas

i.e.

Fubei and Sha’nan with a total area of approximately 317 km

2

were identified in Jiucaiyuan Formation. This study not only provides a geological basis for the efficient hydrocarbon exploration in the Fukang sag of Junggar Basin

but also offers valuable insights for lithologic reservoir exploration in similar regions both domestically and internationally.