| Nowadays, researches of reservoir require higher quantification, to study variation in the reservoir after the investment development, and to find factors that control these changes, and to apply these laws to adjust and improve reservoir development programs; so that to obtain the best development results.Wutonggou group in Xiquan1Well Block is mainly fan delta sedimentation, has good sand distribution continuity. Sand body morphology can be divided into two kinds, sheet sand and banded distribution along provenance. The porosity is generally18to30%, up to31.9%, with an average porosity of24.03%; permeability is generally0.7-954x10-3um2, the average permeability of12.76×10-3um2. Wutonggou group reservoir is characterized by medium porosity and low permeability, ultra-low permeability.Since built postpartum in2007, it can be roughly divided into two phases: construction production stage (May,2007-September,2010), water injection development stage (October,2010-present). By April2012, there were26oil wells, which were open; monthly oil production was3746t, monthly water production was467m3, water cut was11.4%, with cumulative oil production of78713t, and cumulative water production of12039m3. The well number ratio of injection to production was1:3, the monthly injection-production ratio was0.81, the degree of geological reserves recovery of3.3%, the annual liquid production rate of2.3%.Through analysis, reservoir development mainly existed the following questions:(1)oil field was in the early development stage, understanding about the reservoir was not enough;(2)in-depth analysis was not made about water injection development, how to configure the relationship between injection and production, in order to improve ultimate recovery, were to be studied;(3)Xiquan1Well Block was still in the production increasing stage, with low natural decline rate and water cut; how to extend the stable production time and improve individual well oil production phase with no water cut; Enhanced research was needed on rational development technology policy.Based on development status, recovery feature, development effect evaluation, and measures effect analysis, a comprehensive evaluation of reservoir engineering was made in this study. According to preliminary geological understanding, using current advanced three-dimensional reservoir modeling software Petrel, with facies controlling modeling ideas and stochastic simulation methods, geological model was established. Numerical simulation model of Xiquan1Well Block was established, then history matching was made; research of the distribution of the remaining oil was made. Reasonable well pattern, injection-production ratio, injection pressure system, fluid recovery rate, and other measures adjustment suggestion were made to provide a basis for efficient development of the reservoir. Specific contents of this thesis were:1. Block reservoir engineering evaluation. In this paper, a comprehensive evaluation on the reservoir was made from these five aspects:development status analysis (reserve development status, the utilization status of production and absorption cross-section, production status), recovery characteristic analysis, water flooding effect evaluation (water cut rising law, water storage rate, water flooding index), and oil recovery prediction effect analysis. Cumulative water storage rate was0.88; the water flooding index rose quickly, which in January2012was1.2; indicating that water flooding effect changed for the better. It was found that natural energy was low; combined with empirical formula, average water flooding recovery was23.4%. It directed later research of development technology policy.2. Reservoir geological modeling research. Petrel software was applied to establish structural model, sedimentary facies model and property models, visualizing underground reservoirs. Calculation of reserves was2.232million tons, the relative error was-4.1%, compared to2.328million tons of geological reserves.3. Distribution rules of remaining oil and influencing factors analysis. Vertically,3and P3wt12-1was preferably utilized in Wutonggou group, the proportion of cumulative oil reserves was greater than that of the original; P3Wt11-1、3had high remaining reserves, which were good potential layers. Horizontally, the reservoir had hardly been exacted because of shorter injection time; the remaining oil rich region was mainly distributed at the edge of the main body of the oil sands, near the fault and pinch out, as well as the area that was not controlled by the well pattern or where the well pattern was imperfect. The remaining oil was mainly controlled by the fault, well pattern, sand and sedimentary facies.4. Reasonable injection and production system research. According to value from reservoir experience, system testing data and Wang Junkui’s equation theory, rational flow pressure should be about16MPa. Take safety factor of0.85, the maximum allowable flowing pressure in bottom hole of28.18MPa, formation pressure of20.7MPa, so the maximum injection pressure was7.48MPa. Using material balance equation and water drive characteristic curves, combined with empirical formula, the relationship between injection-production ratio and water cut was derived; five sets of programs with the injection ratio of0.8,0.9,1.0,1.1and1.2were designed, to recommend reasonable injection-production ratio of1.1. Otherwise, a set of different fluid recovery rate programs were designed (1.6%,1.9%,2.2%,2.5%and2.8%), to propose the fluid recovery rate of1.9%.5. Development adjustment research. Optimize infill holes, drilling new wells and injection-production ratio program for the next adjustment program; forecast for10years, the cumulative oil production increased by8.16×104t, and the degree of recovery improved by3.57%, compared to the base case. |
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