Research On Steam Flooding Predominant Channel On Middle-depth Heavy Oil Thermal Recovery Reservoir In Qi40 Block

Currently, steam flooding in foreign countries has been in a large-scale industrial application, as heavy oil reservoir, especially the effective way to improve heavy oil reservoir recovery rate after steam stimulation with good application effect. Steam EOR occupies a pivotal position in the EOR (thermal oil). With one data in 2000, for example, in the United States, Canada and Indonesia, the proportion of steam flooding accounted EOR for respectively 55%,75% and 94%.China began to experiment with steam flooding technology and applications from the late 1980s. In the late 1980s and early 1990s, China had conducted eight steam flooding pilot tests in the Xinjiang Oilfield and Liaohe Oilfield, and had achieved a major breakthrough. Steam flooding has become a widely used heavy oil recovery technology, as an important way to develop heavy oil conversion technology, which has been successfully applied in.The Qi 40 block of Liaohe Oilfield is one of the biggest blocks, in which our country has implemented steam flooding. Since 1998, it has gone through the pilot test, expanding test and industrialization application three stages. The construction of large-scale industrial transferring steam flooding began to be conducted, in March 2008, turn drive in a total of 139 well groups were completed, while the block transferred into a comprehensive steam flooding industrial development. In 2011, year production of crude oil in Qi 40 block was 600,000 tons,500,000 tons more than the origin way, stepping into stable stage. So far, main body of Qi 40 block has been already in the late stages of steam flooding, the overall production has a downward trend. Because with the deepening thermal recovery development and continuous improvement of steam drive maturity, constrained by the reservoir heterogeneity, there is often a even steam phenomenon in the long-term steam injection development process, steam ability of high and low permeation layer have a large difference in the longitudinal direction, which makes the injected steam easily rush on along the smaller resistance parts of high permeation layer, gradually forms steam flooding advantage channel.After the formation of steam flooding advantage channels, the heterogeneity increases, contradictions of various development highlights, making injected steam rush on along the priority of this path forming a distinct advantage, or even steam channeling. The steam directly from the steam injection wells flees into production wells, while steam flooding effect of the part of low permeation layer is relatively poor, and some are not even spread by steams layers to form so-called "dead oil area", thus leading to residual oil. It causes steam breakthrough in single layer and single direction of plane steam flooding worsening, vertical steam channel of the main reservoir increases, resulting in uneven use of oil, low heat utilization, impacting steam flooding development effect. Therefore, in order to effectively identify the advantages of steam flooding channels and select associating dynamic controlling measures to improve the effectiveness of steam flooding, it is necessary to deepen the research on thermal recovery reservoir steam flooding advantage channels.In this paper, Lianhua oil layer of 65 well group as the main part of steam flooding of Qi 40 block in Liaohe Oilfield is the research target, comprehensively using steam absorption profiles, production profiles, well temperature profiles as well as the production and development features of oil field development dynamic data, describing dynamic response characteristics of steam flooding advantage channel in study layers, analyzing the connectivity of steam injection wells and production wells, applying various experiment results of analysis assay data and physical simulation of system coring wells, analyzing changing regular patterns of macroscopic and microscopic characteristics of thermal recovery reservoirs before and after steam flooding, taking advantage of geological static data to analyze geological condition forming steam flooding advantage channel in target layer on basis of research on the formation mechanism of steam flooding advantage channel and dynamic response characteristics of development, and to determine the location of its formation, deciding the index weight through gray correlation analysis method, applying the fuzzy clustering analysis method to classify steam advantage channel and establish criteria, according to evaluation criteria established, applying fuzzy pattern recognition method to establish evaluation method of steam flooding advantage channel based on geological parameters, comprehensively evaluating the causing sand body in target layers in whole area to predict the distribution of advantage channels in the region. Finally, using the above theory to conduct contrast and analysis of distribution and geological conditions of steam flooding advantage channels of 65 well group of Qi 40 Block, the results show good agreement, verifying the validity of the method.Through the study of steam flooding advantage channel of thermal recovery reservoir, the following knowledge and conclusions have been mainly made:1. Stratified steam flooding development dynamic data are comprehensively used to qualitatively identify layers of steam flooding advantage channels, the performance characteristics are:steam injection wells vapor-absorption profiles show a large proportion of absorption, and the onrush in single layer on vertical are serious. Differences in production liquid curves variation of production liquid profiles are big, and differences are significant in vertical liquid production situation and with the passage of time, liquid production capacity of the main producing liquid layer gradually increases. High-temperature well segments appear in well temperature profiles. steam production wells also show that day production of liquid and water-bearing rates increases significantly after steam flooding, and daily oil production overall has a upward trend, indicating effective steam flooding.2. Geological affecting factors of the formation of steam flooding advantage channels include:sedimentary causing sand body characteristics (lithology, reservoir thickness and sedimentary microfacies), reservoir properties (porosity, permeability), reservoir heterogeneity (plane, the inner layer and inter-layer), oil-bearing property and structural features (dip angle) and etc.3. Using fuzzy clustering analysis method, combining with the dynamic response characteristics of development, determining five evaluation parameters, two types of steam flooding advantage channel can be divided:Class Ⅰ channel forms in the river development area, effective sand thickness is generally 4.4m. The average penetration is 2.651μm2, and variation coefficient is 0.59, and the average frequency of mezzanines is 0.25 pieces/m. While Class II mainly forms in the river edge microfacies, the average effective sand thickness is 2m, average permeability is 2.370μm2, variation coefficient is 0.52, and the average frequency of mezzanines is 0.45 pieces/m. The above classification results show that:within the constraints of thermal recovery and internal layer steam overlay, after the formation of steam flooding advantage channel, reservoir properties have been better, the heterogeneity in layers enhances.4. According to the geological, logging, development and other information, on basis of evaluation criteria of steam flooding advantage channels established by fuzzy clustering analysis method, applying fuzzy pattern recognition method to conduct a comprehensive evaluation of single sand body of the main target layers by points, classification of steam flooding advantage channels in the study area and the reflection of their features are more objective and accurate, compared with geological conditions and analyzing, and it illustrates this evaluation method is feasible for research on steam flooding advantage channels in the region.