Overpressure origin and its effects on petroleum accumulation in the conglomerate oil province in Mahu Sag, Junggar Basin, NW China

Jun, Li; Tang, Yong; Wu, Tianyu; Zhao, Junping; Wu, Heyuan; Wu, Wenzhuo; Bai, Yubin

doi:10.1016/s1876-3804(20)60088-x

Cited by 42 publications

(10 citation statements)

References 26 publications

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“…To calculate the formation pressure in this study, the Philippone formula improved by Liu et al (2000) is used:

{bold-italicP}_{bold-italicf} = \frac{{bold-italiclnV}_{bold-italicm} ‐ lnV}{{bold-italiclnV}_{bold-italicm} ‐ {bold-italiclnV}_{bold-italicf}} {bold-italicP}_{bold-italicov}

where

{bold-italicP}_{bold-italicf}

is the formation pressure (MPa),

{bold-italicV}_{bold-italicm}

is that compressional velocity for the reservoir rock whose effective porosity is near zero (m/s),

V

is the ground layer velocity (m/s),

{bold-italicV}_{bold-italicf}

is approximately that compressional velocity where the rigidity is near zero (m/s),

{bold-italicP}_{bold-italicov}

is the overburden load pressure (MPa),

{bold-italicV}_{bold-italicm}

and

{bold-italicV}_{bold-italicf}

are linearly increasing velocities with respect to reflection time corresponding to compaction rates with overburden load and

{bold-italicV}_{bold-italicm}

and

{bold-italicV}_{bold-italicf}

can be obtained from logging data and are constants (Fillippone, 1983).…”

Section: Methodsmentioning

confidence: 99%

Hydrocarbon dominant migration direction and accumulation mode in Qijiang area, Sichuan Basin, China

Cheng

Ding

et al. 2023

Geological Journal

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The high‐quality hydrocarbon source rocks developed in the Longtan Formation of the Qijiang area and the good reservoir capacity of the overlying dolomite of the Jialingjiang Formation indicate that the area has great exploration potential. To clarify the hydrocarbon migration and accumulation characteristics of the area, the fluid potential of the Longtan Formation in the Qijiang area in the Early Jurassic was determined. The direction of the maximum negative gradient of the fluid potential indicates the direction of the primary migration of hydrocarbons, and the structural ridge theory is used to analyse the direction of the secondary migration of hydrocarbons. The results show that the fluid potential of the hydrocarbon source rocks of the Longtan Formation in the Early Jurassic is characterized by the alternate distribution of high potential zones and low‐potential zones. The central syncline, eastern syncline and western syncline are drainage zones and high potential zones, while the Shiyougou structural belt and Fo'er Ya structural belt are supply zones and low‐potential zones. The oil and gas fluids migrate from the east–west direction to the anticlinal zone for the primary migration; the structural ridge controls the secondary migration of oil and gas in the low‐potential area along the north–south direction, resulting in a zonal distribution of oil and gas traps along the structural ridge. By combining fluid potential and structural ridge characteristics to determine the dominant direction of primary and secondary hydrocarbon migration, a model of hydrocarbon migration and accumulation in the Qijiang area is developed, which provides an important basis for finding hydrocarbon reservoirs.

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“…To calculate the formation pressure in this study, the Philippone formula improved by Liu et al (2000) is used:

{bold-italicP}_{bold-italicf} = \frac{{bold-italiclnV}_{bold-italicm} ‐ lnV}{{bold-italiclnV}_{bold-italicm} ‐ {bold-italiclnV}_{bold-italicf}} {bold-italicP}_{bold-italicov}

where

{bold-italicP}_{bold-italicf}

is the formation pressure (MPa),

{bold-italicV}_{bold-italicm}

is that compressional velocity for the reservoir rock whose effective porosity is near zero (m/s),

V

is the ground layer velocity (m/s),

{bold-italicV}_{bold-italicf}

is approximately that compressional velocity where the rigidity is near zero (m/s),

{bold-italicP}_{bold-italicov}

is the overburden load pressure (MPa),

{bold-italicV}_{bold-italicm}

and

{bold-italicV}_{bold-italicf}

are linearly increasing velocities with respect to reflection time corresponding to compaction rates with overburden load and

{bold-italicV}_{bold-italicm}

and

{bold-italicV}_{bold-italicf}

can be obtained from logging data and are constants (Fillippone, 1983).…”

Section: Methodsmentioning

confidence: 99%

Hydrocarbon dominant migration direction and accumulation mode in Qijiang area, Sichuan Basin, China

Cheng

Ding

et al. 2023

Geological Journal

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“…The Mahu sag is adjacent to the Kebai and Wuxia large fault zones in the northwest [34], the Yingxi sag in the east, the Dabasong-Xiayan uplift in the southeast, and the Zhongguai uplift in the southwest [25,35] (Figure 1a), and it was developed on the pre-Carboniferous folded basement [27]. The Lower Permian Fengcheng Formation is the main source of rock formation in the Mahu sag [36], with a maximum formation thickness of 1500 m [26]. It is the oldest alkali lacustrine source rock discovered in the world so far [37].…”

Section: Geological Setting and Samplesmentioning

confidence: 99%

Diagenesis of the Permian Fengcheng Formation in the Mahu Sag, Junggar Basin, China

Bai,

Liang,

Dai

et al. 2023

Applied Sciences

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The Fengcheng Formation in the Mahu sag of the Junggar Basin was primarily composed of detritus, pyroclastic material, carbonates, and evaporites. In order to establish the diagenesis pathways of the Fengcheng Formation, some methods of polarized light microscope, SEM, CL, EPMA, LR, and fluid inclusion analysis were applied to discuss the diagenesis process. The results showed the following: (a) The formation of an alkaline lake was the result of the influence of a high concentration of sodium-rich sources, and it led to the preservation of alkaline minerals in the stratum. (b) After the sediments were buried, three mineral assemblages were formed in the Fengcheng Formation, which are carbonate mineral assemblages (i.e., calcite + ferreous dolomite), reedmergnerite and carbonate mineral assemblages (i.e., reedmergnerite + calcite + ferreous dolomite), and reedmergnerite and alkaline mineral assemblages (i.e., reedmergnerite + shortite + trona), respectively. (c) According to the homogenization temperature of reedmergnerite primary fluid inclusions, the alkaline diagenesis of Fengcheng Formation was divided into an early stage (≤100 °C) and a middle stage (>100 °C), respectively. The earlier stage is marked by the formation of ferrous saddle dolomite, quartz dissolution, and the agglutination of laumontite. These processes occurred under normal burial conditions. The latter is marked by the reedmergnerite’s appearance, which is correlated with the deep hydrothermal activity controlled by faults. (d) Based on sedimentary and diagenetic factors, including climate, provenance, diagenetic surroundings, and the action of subsurface fluid, the alkaline deposition-diagenesis model for shale series in four stages of the Fengcheng Formation was established.

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“…In this case, a pore pressure exceeding the hydrostatic pressure develops. Disequilibrium compaction is the main origin of overpressure in rapidly deposited fine-grained systems such as deltas (Osborne and Swarbrick, 1997;Opara, 2010;Li et al, 2020). However, the overpressure size created by the increasing vertical load is limited.…”

Section: Disequilibrium Compactionmentioning

confidence: 99%

Present-day overpressure in southern Tunisia: Characterization, possible causes and implications for drilling operations

Akrout

Ahmadi

Mercier

et al. 2021

Journal of African Earth Sciences

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Overpressure origin and its effects on petroleum accumulation in the conglomerate oil province in Mahu Sag, Junggar Basin, NW China

Cited by 42 publications

References 26 publications

Hydrocarbon dominant migration direction and accumulation mode in Qijiang area, Sichuan Basin, China

Hydrocarbon dominant migration direction and accumulation mode in Qijiang area, Sichuan Basin, China

Diagenesis of the Permian Fengcheng Formation in the Mahu Sag, Junggar Basin, China

Present-day overpressure in southern Tunisia: Characterization, possible causes and implications for drilling operations

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