摘要
KeLa-2 gas reservoir is the largest uncompartimentalized gas field so far discovered in China, with a reserve of hundreds of billions of cubic meters of dry gas. It has such features as extremely long interval (550m), high pressure (74.5MPa) and pressure coefficient (2.022). Gas reservoirs with a pressure coefficient of over 2.0 are not commonly found. The abnormal high-pressure reservoirs are quite different in characteristic and performance during the process of depletion exploitation. Therefore, it is necessary to know the property of pressure sensitivity for this abnormal high-pressure reservoir. The aim of this paper is to test the reservoir pressure sensitivity and to analyze its effect on the deliverability of gas. Through some experiments, the permeability change with the confining pressure of rock samples from KeLa-2 abnormal high-pressure gas reservoir is measured. A power function is used to match the measured data, and to derive an empirical equation to describe the change of permeability through the change of the reservoir pressure or effective overburden pressure. Considering the permeability change during the development of reservoirs, a conventional deliverability equation is modified, and the deliverability curve for KeLa-2 gas reservoir is predicted. The research indicates that the extent of the pressure sensitivity of rock samples from KeLa-2 is higher than that from the Daqing oilfield. KeLa-2 reservoir rock has the feature of an undercompaction state. The pressure sensitivity of a reservoir may decrease the well deliverability. It is concluded that for KeLa-2 reservoir the predicted absolute open flow (AOF), when the pressure sensitivity is taken into account, is approximately 70% of the AOF when permeability is constant and does not change with pressure.
KeLa-2 gas reservoir is the largest uncompartimentalized gas field so far discovered in China, with a reserve of hundreds of billions of cubic meters of dry gas. It has such features as extremely long interval (550m), high pressure (74.5MPa) and pressure coefficient (2.022). Gas reservoirs with a pressure coefficient of over 2.0 are not commonly found. The abnormal high-pressure reservoirs are quite different in characteristic and performance during the process of depletion exploitation. Therefore, it is necessary to know the property of pressure sensitivity for this abnormal high-pressure reservoir. The aim of this paper is to test the reservoir pressure sensitivity and to analyze its effect on the deliverability of gas. Through some experiments, the permeability change with the confining pressure of rock samples from KeLa-2 abnormal high-pressure gas reservoir is measured. A power function is used to match the measured data, and to derive an empirical equation to describe the change of permeability through the change of the reservoir pressure or effective overburden pressure. Considering the permeability change during the development of reservoirs, a conventional deliverability equation is modified, and the deliverability curve for KeLa-2 gas reservoir is predicted. The research indicates that the extent of the pressure sensitivity of rock samples from KeLa-2 is higher than that from the Daqing oilfield. KeLa-2 reservoir rock has the feature of an undercompaction state. The pressure sensitivity of a reservoir may decrease the well deliverability. It is concluded that for KeLa-2 reservoir the predicted absolute open flow (AOF), when the pressure sensitivity is taken into account, is approximately 70% of the AOF when permeability is constant and does not change with pressure.
