Depositional features of the Middle Jurassic formation of Field N and their influence on optimal drilling schedule

Scientific and Technical Challenges in the Well Drilling Progress

Mishina, D.^1,2 ; Rukavishnikov, V.^1 ; Belozerov, B.^2 ; Bochkov, A.^2

Tomsk Polytechnic University, Tomsk, Russia^1

LLC Gazpromneft Science and Technology Center, Saint-Petersburg, Russia^2

关键词: Bearing layers;    Geological information;    Middle Jurassic;    Petrophysical information;    Precise determinations;    Probability maps;    Production test;    Saturated zone;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/24/1/012049/pdf
DOI  :  10.1088/1755-1315/24/1/012049

来源: IOP

【 摘 要 】

The Middle Jurassic formation of Field N represented by 4 hydrodynamically connected layers (J5-6, J4, J3 and J2) contains 42% of the field STOIIP. The J2-6 formation is characterized as a gas-oil-condensate massive lithologically and tectonically screened accumulation with a gas cap (J2, J3 layers) and bottom water (J5-6 layer). Oil is predominantly in the J3 and J4 layers. There is a high risk of early gas coning from gas-bearing layers to oil producing wells determined on the basis of production test results, which can significantly decrease the life of the well. To select a more optimal drilling schedule, it is necessary to take the risk of early gas coning into account and determine distinctive features within the gas- saturated zone that can reduce it. The presence of a thick shale barrier between the J2 and J3 layers with thicknesses varying from 0 to 30 m is recognized as the beginning of a transgression cycle, and if the gas cap is only in the J2 layer, this barrier with the thickness of more than 5 m can extensively prevent early gas coning into oil producing wells. The integration of geological information represented by the probability map constructed and petrophysical information represented by the kh map provide the more precise determination of an optimal drilling schedule.