Gas Testing Flowback Rules of Shallow Shale Gas Horizontal Wells in TY Block of Zhaotong

doi:10.7657/XJPG20200411

Abstract

Abstract:

Aiming at the shallow burial, low formation energy and high flowback rate of the shale gas reservoirs in Taiyang block of Zhaotong National Shale Gas Demonstration Area in the southern Sichuan basin, it is of great significance to accurately master the laws of gas testing and flowback of horizontal wells in shallow shale gas reservoirs and to formulate a specific test system for improving single well recovery. For this reason, drawing lessons from the gas testing law of the horizontal wells in the middle and deep shale gas strata in the adjacent block, and combining with the knowledge and practical experience of the water drainage and gas production law of the tested wells in the study area, the paper divides the gas testing process in the horizontal wells in the study area into 6 stages, summarizes the laws of gas test and flowback and formulates the corresponding production system on the basis of gas-liquid two-phase percolation theory and stress sensitivity analysis methods. The results show that the optimum well soak time, choke diameter and choke adjusting timing can be determined by taking the key parameters including daily gas production, daily water production and wellhead pressure as evaluation criteria, which can greatly reduce reservoir damages caused by stress sensitivity. Then gas testing productivity can be obtained and well recovery can be improved as well. Based on which, 2 sets of standard charts have been established for gas testing and flowback in horizontal wells in shallow shale gas reservoirs in the study area, and the actual application in field production has proved the good effect of the charts.

Key words: Zhaotong, Taiyang block, shallow shale gas, horizontal well, well soak time, gas testing, flowback rule

CLC Number:

TE357

HUANG Xiaoqing, HAN Yongshen, YANG Qing, ZHOU Yun, YUAN Xiaojun, LIU Ye. Gas Testing Flowback Rules of Shallow Shale Gas Horizontal Wells in TY Block of Zhaotong[J]. Xinjiang Petroleum Geology, 2020, 41(4): 457-463.

Figures/Tables 9

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井区	目的层埋深/m	最小水平主应力/MPa	最大水平主应力/MPa	上覆地层应力/MPa	地层压力系数
HJB-108井区	2 509	56.5	71.0	61.0	2.00
TY-118井区	2 246	44.7	65.4	57.3	1.61
TY-102井区	760	16.0	26.2	18.8	1.43
TY-1井区	960	20.2	24.2	24.0	1.22

储集层分类	总有机碳含量/%	有效孔隙度/%	脆性矿物含量/%	含气量（/m³·t^-1）
Ⅰ类储集层	>3	>5	>55	>3
Ⅱ类储集层	2~3	3~5	45~55	2~3
Ⅲ类储集层	1~2	2~3	30~45	1~2
非储集层	<1	<2	<30	<1