Microscopic Oil Mobility in Tight Conglomerate Reservoirs Under Different Development Modes, Mahu Sag

doi:10.7657/XJPG20240309

Abstract

Abstract:

In order to evaluate the oil mobility in the tight sandy conglomerate reservoirs of the Triassic Baikouquan formation in the Mahu sag, the distribution characteristics of movable oil in typical rock samples from Type Ⅰ and Type Ⅱ reservoirs were compared through imbibition, centrifugation, and huff-n-puff tests. For the low-permeability conglomerate reservoirs in the Mahu sag, the imbibition oil recovery is related to the pore structure of the rock. The higher the proportion of small pores, the better the imbibition effect. After 144 hours of oil displacement by imbibition, the recovery rate can reach 30.9%, but the oil displacement process is slow, with low utilization of large pores. Under reservoir pressure of 40 MPa and reservoir temperature, during three cycles of CO₂ huff-n-puff process, the recovery percent of each round increase, with the highest increase observed in the first cycle, reaching an oil exchange ratio of 27%. As the huff-n-puff cycle increases, the increment in recovery percent gradually decreases, and the oil exchange ratio of N₂ huff-n-puff in the first cycle is 15%. Therefore, CO₂ huff-n-puff has the best development effect.

Key words: Mahu sag, Baikouquan formation, tight conglomerate reservoir, movable oil saturation, NMR, displacement efficiency

CLC Number:

TE122.1

WAN Tao, ZHANG Jing, DONG Yan. Microscopic Oil Mobility in Tight Conglomerate Reservoirs Under Different Development Modes, Mahu Sag[J]. Xinjiang Petroleum Geology, 2024, 45(3): 327-333.

Figures/Tables 10

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区块	井名	深度/m	孔隙度/%	渗透率/mD	岩性
玛18区块	A井	3 989.5	10.3	1.91	含砂中砾岩
玛18区块	A井	3 911.5	11.8	2.43	含砂细砾岩
玛18区块	A井	3 898.2	7.2	0.84	含砂中砾岩
玛18区块	B井	3 898.2	9.8	0.55	含砂中砾岩
玛18区块	B井	3 895.7	3.9	0.10	含砂细砾岩
玛18区块	B井	3 892.7	8.6	0.66	含砂中砾岩
玛131区块	C井	3 894.5	7.7	2.08	含砂中砾岩
玛131区块	C井	3 886.5	6.8	0.89	砂质中砾岩
玛131区块	D井	3 888.1	6.6	6.11	含砂细砾岩
玛131区块	D井	3 884.1	8.1	3.38	含砂中砾岩

渗吸时间/h	玛18区块采出程度/%			玛131区块采出程度/%
渗吸时间/h	小孔隙	大孔隙	总采出程度	小孔隙	大孔隙	总采出程度
12	4.06	1.91	5.97	7.17	3.38	10.55
24	8.57	2.74	11.31	16.36	7.05	23.41
48	15.00	4.08	19.08	19.73	9.93	29.66
72	14.91	5.48	20.39	20.11	9.80	29.91
144	17.14	6.07	23.21	21.19	9.77	30.96

转速/ （r·min^-1）	玛18区块动用程度/%			玛131区块动用程度/%
转速/ （r·min^-1）	小孔隙	大孔隙	总动用程度	小孔隙	大孔隙	总动用程度
0	0	0	0	0	0	0
1 500	2	2	4	2	1	3
3 000	3	4	7	3	5	8
5 000	4	8	12	3	7	10
7 000	4	11	15	3	9	12