A Study on the Remaining Oil After Strong Base ASP flooding

Abstract

Abstract ASP flooding tests in Daqing oilfield show that it can greatly enhance oil recovery and provide a powerful technical support for sustainable development of the oilfield.At present, ASP flooding in Daqing oil field has entered commercial popularization stage and the supporting technologies such as reservoir engineering, production engineering, surface engineering involved with multi-disciplinary, chemical agent quality inspection and field injection have been formed.However, there still lacks in-depth recognition about reservoir developing conditions and remaining oil distribution after alkali ASP flooding. Therefore, on the basis of analysis of dynamic and static data, application data from newly drilled wells and coring data before and after ASP flooding, this paper gives a clear understanding of the reservoir developing condition and oil displacement effect and confirms remaining oil distribution characteristics and its forming causes from macroscopic to microcosmic perspectives and from horizontal to vertical directions then to innerlayers through application of geological research, numerical simulation, lab core detection, nuclear magnetic resonance (NMR) and confocal laser scanning technology. From macroscopic perspective, there is less remaining oil scattering on the plane due to imperfect relationship between injection and production; Vertically, the top of sand body is where remaining oil richly gatheres.Alkali ASP flooding's effect is remarkable for remaining oil and heavy constituents of oil have dramaticly reduced, Especially for membranous remaining oil on the pore surface, and intergranular adsorption of remaining oil has added. Daqing Oilfield is the earliest one to carry out ASP commercial field test and popularization, and has acquired abundant knowledge about it. But systematic evaluation and analysis of alkali ASP flooding hasn't been formed for there lacks further understanding of reservoirs’producing performance and remaining oil's distribution after alkali ASP flooding. In the A block of thick reservoir alkali ASP commercial field test which has been finished, there are 258 wells newly drilled (including 1 sealed coring well) with well spacing density of 177 wells/ km2.Dynamic data and coring wells’data from the test area are effectively combined with newly-drilled wells’logging information to study microscopic remaining oil in the cores before and after ASP flooding; Meanwile, Methods such as statistic analysis, core displacement, numerical simulation, nuclear magnetic resonance, Carbon/oxygen spectral logging, and dynamic comprehensive analysis are applied with confocal laser scanning technique to ideally detect and analyze remaining oil's type and distribution. It will provide guidance for further adjustments during alkali ASP flooding and for EOR research after ASP flooding.