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Mechanical Compaction Effects On Low Porosity And Low Permeability Reservoirs

Posted on:2015-01-12Degree:MasterType:Thesis
Country:ChinaCandidate:Y N JiangFull Text:PDF
GTID:2250330428990877Subject:Mineralogy, petrology, ore deposits
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China’s Bohai Bay Basin, which the whole basin of proven crude oil reserveshave exceeded100×108t is China’s largest oil discovery basin in eastern continentalrift basins, has been nearly five decades of exploration history. Bohai Sea developedmany Paleogene hydrocarbon-rich depressions, level of exploration is low, has greatexploration potential, so for petrological characteristics of the region studies theeffects of diagenesis on reservoir properties discussed the evolution of reservoirproperties.In this paper,we use data analysis to determine the type of reservoir sandstones,components and content of the grains, particle size and clastic reservoirs sorting todetermine rock types and structures, and choose mechanical compaction of samples todetermine the particle experiments selected; porosity and permeability of thereservoir properties to establish criteria for the classification, porosity andpermeability data analysis combined with low porosity and permeability reservoirquality index, and compare the experimental results which we measured.According to the information and observations of polarization microscope, thetypes of reservoir sandstone rock are mainly feldspathic lithic sandstone, lithicfeldspathic sandstone, feldspathic sandstones, and a small part of lithic sandstone.There are mainly fine-grained granularity, and less medium-grained andcoarse-grained. Sorting of the area is generally medium. Contact between the grains ismainly long and convave-convex. The strength of contact between the grains relywith increasing depth, and tranform from weak to strong compaction.Quality of reservoir is an important factor affecting the exploration anddevelopment, study the controlling factors of reservoir quality is useful to theexploration and development of oil fields. Study of the core porosity data in the BohaiBasin, porosity decreases with increasing depth, according to the reservoir porosity and permeability reservoir is divided into seven categories, low porosity and lowpermeability reservoir is divided into four categories: tight reservoir Ⅲ, tightreservoir Ⅱ, tight reservoirⅠ and low porosity reservoirs. The majority of theregion’s reservoirs is tight reservoirs and low-medium porosity reservoirs. Therefore,exploration and development of low porosity reservoirs and tight reservoir is focusedon exploration in Bohai basin. Reservoir quality factor RQI the value of which lessthan0.379mD is low porosity and low permeability reservoirs. The quality ofexploration and development of reservoir is difficult to predict, and we need toexplore the reservoir quick and simple method for determining quality. Reservoirquality index (RQI) is a reaction parameters which combines the effect of porosityand permeability.We designed and completed the study area for the five experiments of fourgroups which is based on the former study of composition and content of grains andstructure of the study area. The results showed that during compactions, the samplesporosity and permeability were reduced with increasing depth. Five experimentsporosity and permeability all have a turning point at the depth of3000m, and theporosity two experiments which with part of plastic grains decreased faster in therange of0-1000m is in rapid compaction stage, porosity appearing a turning point atthe depth of1000m, compaction rate slows down, and after compaction of3000m,the rate is further reduced, compaction is in a slow compaction stage. The seriategrains’ original porosity lower than other groups of experiments suggests that grainsize distribution of compaction impacts larger part of experimental results. Althoughthe experiment samples with plastic grains which is only25%of the total samplegrains, the porosity of the experimental result that reduction are faster than thesamples of pure rigidity grains. The result shows that the plastic grains is an importantfactor in controlling the physical propertie. The experimental of plastic grainsconsistent results are more likely adjoining with the actual formation, comparing withthe samples of pure rigidity grains. Therefore, the grain composition and content,content and structure of the reservoir plastic particles are an important influencereservoir quality are important judgment factor of the exploration process.
Keywords/Search Tags:Bohai Bay Basin, Paleogene, reservoir properties, diagenesis, mechanicalcompaction experiments
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