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Reserves Calculation Of Heterogenous Hydrocarbon Reservoir

Posted on:2009-03-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:C G LiangFull Text:PDF
GTID:1100360245999598Subject:Geological Resources and Geological Engineering
Abstract/Summary:PDF Full Text Request
Reserves calculation is a long-time work throughgoing exploration and development. With the addition of the data and the knowledge of the reservoirs, reserves will be recounted. The reliability of reserves calculation influenced the exploration and development decision. And how can we calculate hydrocarbon reservoir accurately? The key is having correct knowledge and accurate parameters of hydrocarbon reservoirs. This thesis took shallow oil reservoir in Qaidam basin as the study area which was typical with abundant data of the core observation, the information of laboratory analysis, thin slices, cast thin slices, X- diffraction, mercury penetration, infiltration curve, well logging, well testing, logging (including conventional logging, array induction imaging log and FMI), seismic, surface survey, production performance, etc. Reservoir heterogeneity was studied from five aspects. They were structure, sedimentation, reservoir, diagenic metamorphism and fluid property. This paper analyzed the influences of reservoir heterogeneity in dividing reserves calculation unit and accounting parameter. On the basis of analysis,hydrocarbon reservoir has been calculated. The conclusions are as follows:1,Using the data of core analyses, conventional logging and FMI, the limestone marker bed(K2-1) with formal of"twin bayonet"on RT has been recognized inside N22.Uniting characteristic fossil in bottom of N22,the formation was divided into 9 groups and 37 sublayers in N22 and 3 groups and 14 sublayers in N21 according to the rule"cycle comparison, step control". The oil layers distribute from 79m to 620m in vertical orientation and the individual bed is thin(from 1m to 2.8m)and there is no unite oil/water boundary in the region of interest. Seeing that features, the reserves in vertical have been divided in 51 calculation units.2,The deposition characteristics have been analyzed from depositional setting, provenance orientation, and sedimentary structure. According to analyses ofδ13c andδ18o, depositional environment has been built-up quantitatively and palaeosalinity also has been confirmed. Based on the preceding research, sedimentary microfacies have been subdivided and depositional model has been established. Lacustrine facies has been divided into meare and semi-abyss. There are three microfacies in meare included granule sands, limestone and sand bank. There is corcagh microfacies in semi-abyss. The reservoir rock types in the region of interest are grain limestone, algal limestone, cryptite, siltstone, muddy limestone and mudstone. The thesis identified as a result of changes in the deposition causing the heterogeneity in plane, and then the geological oil reserves have been calculated in accordance with the areal heterogeneity.3,Based on the data of core analysis, bore logging, array induction imaging log and FMI, porosity and permeability model were built using regression analysis. Through testing 45 rock samples, a, b, m, n value were obtained and used to calculate single-layer oil saturation value using the Archie formula. According to the theory of laterolog and inductolog, resistivity ratio and cross plot were used to identification effective thickness. Effective thickness was identified delicately in 103 wells. Based on the over work, active porosity and oil saturation was calculated accurately.4,According to observation of 100 pieces of the thin slices, cast thin slices and 383m core in three wells, the chief diagenesis in this area were compaction, cementation, denudation and cataclasis. Cementation and denudation were universally influenced active porosity this area. The intergranular pores, residual pores and secondary pores were formed in thin carbonated reservoir of lacustrine facies.5,The influence of reservoir heterogeneity to reservoir calculation was analyzed systematically using actual data. And the conclusions were as follows:①The principal reason leading to oil distribution unequal is interior structural feature of reservoir in structural hydrocarbon reservoir. Oil and gas was stored easily in high structure. The gravitational differentiation of oil and gas displayed the interior heterogeneity of reservoir. When structure map changed, oil area must be changed.②Sedimentary facies controlled the distribution of reservoir. The beneficial reservoir was usually developed in main facies belt. Difference depositional mode caused the difference physical property of reservoir. And the difference directly influenced the distribution of oil and gas in reservoir. So sedimentary facies is the geological source caused reservoir heterogeneity.③Structural feature, lithology, physical property must be take into account when dividing reserves calculation unit and calculating reserves parameters.④The heterogeneity of fluid affected evaluation of SO ,oil density and volume factor.⑤Sedimentary microfacies and diagenesis influenced pore structure and reservoir physical property and controlled the characteristics of hydrocarbon bearing reservoir, so that it affected the accuracy of calculation of reserves.6,On the basis of the above-mentioned research the conception of hydrocarbon reservoir heterogeneity unit was developed. And this paper introduced the method to divide the hydrocarbon reservoir heterogeneity unit in a case study. The result shows that using divided hydrocarbon reservoir heterogeneity unit in calculation of reserves is more accurately than normal method(oil-13.4%,-4.7%, associated gas-14.8%). Using this method successfully submit discovered reserves to reserves commission.
Keywords/Search Tags:Lacustrine facies carbonate rock, Logging geological evaluation, Reserves calculation, Reservoir heterogeneity unit, You Quanzi oilfield
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