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Reserve Evaluation And Development Technique For Low Porosity And Low Permeability Gas Of Bawu Area In South Songliao Basin

Posted on:2008-07-18Degree:MasterType:Thesis
Country:ChinaCandidate:H W JiaFull Text:PDF
GTID:2120360242460081Subject:Geological Engineering
Abstract/Summary:PDF Full Text Request
Bawu Gas Field is located in Gongzhuling City of Jilin Province, which structure is located at the central structural belt in the northeast of Shiwu Fault Depression of southeast Uplift of the southeast Songliao Basin. It borders upon Siwujiazi Oil and Gas Field to the east and Houwujiahu Gas Field to the south. In 1980s, the detailed survey had been started. In 1995, development stage had run. Up to date, the proven reserve of natural gas is about 29 hundred million cubic meters and 47 wells of the exploratory wells and development wells had been drilled. Up to 2006, the proven reserve and newly increased proven reserve of Bawu Gas Field had been examined and commented by National Reserve committee four times early or late. The accumulate proven reserve of the deep is 10.67×10~8m~3 and 2.1×10~8m~3 of gas. It is proven that Bawu Gas Field is a medium and mini type of gas field.The complicate geological characteristics are more obvious along with the development continuously. The geological problems of development need more in-depth study for the regularities of distribution of reservoir beds of gas in vertical and non-homogeneous features of reservoir beds. Especially the problems, that are the particularity of the deep reservoirs , the short of stable production period of single well and rapid descending of gas well production and so on, badly effect the level gas extraction and the life of the gas field. So to increase the level of gas extraction and slowly drop the rate of descending, the scientific system of exploitation is improved father. To realize the maximum economic value of the difficult workable reserve, fracturing technology is perfected. In this subject, combining with the practical situation, it is in detail studied to deep structure, reservoir and characteristics of Bawu Gas Field. The reserve is re-calculated. The difficult workable reserve is evaluated and exploitation technology is deeply studied.In this paper, the geological situation, strata sedimentary features, structural features, faults and reservoir features and so on were discussed in detail and the features of dense reservoir in deep and the types of the gas reservoir were studied. Based upon sedimentary facies, structure and reservoir, geologic reserve was calculated and the quantity and distribution of the difficult workable reserve was made certain. The restrict factors of the difficult workable reserve was found out. The means of planning reserve and increasing recovery ratio was also found out. Fracturing technology was specially studied. Following the rule of production of gas and oil, the means of increasing production was implemented.The deep dense reservoir of Bawu Gas FieldThe types of sedimentary facies: Formation Shahezi belongs to coarse delta sedimentation of braiding channel entering into lake-basin. The sedimentary evolution of Formation Yingcheng is similar to Formation Shahezi, in the sedimentary area, the types of sedimentary is also belong to delta sedimentation of braiding channel and lake sedimentation mainly.The evaluation of deep dense reservoir features:In the lower of Formation Denglouku, Formation Yingcheng, Formation Shahezi, the reservoir bed is dense; the rock structure of reservoir is complicated; the room of reservoir is small. There are two effects. One is coarse lithology, and the other is stronger compaction. This indicates that reservoir's lithology is not good and the cementation is dense. The litholog includes mainly medium, fine sandstone and pebbled sandstone.The Features of deep dense reservoir of Bawu Gas FieldThe distribution of the layer of gas mainly indicates several aspects below: There are big differences of developing extent of gas layer among the wells,which gas layers are dispersed in vertical, the scale of pure gas area is small,most gas area of the layers is single-well controlled, outwards changing intogas-bearing water layers and water layers.ThThe evaluation of deep dense reservoir of Bawu Gas FieldThere are many more gas-bearing water layers in Bawu Gas Field in vertical. Theextent of depth is big one. Gas reservoirs are dispersed. The relationship betweenwater and gas is complicated. The level of mineralization of the water is low. Thetype of water basically belongs to saleratus. The reservoir beds are ofhomogeneity and medium heterogeneity. The gas reservoir is reservoir oflithology, which is mainly controlled with structure. The amount of gas reservoiris large. The dimensions are small and the geologic condition is complex. Thegas reservoirs are mainly in layers and the thickness is several meters to about tenmeters. The dynamical features of the gas reservoir reflect that the gas reservoirsare mainly the close type of limit capability. Majorities are mainly self-drivenwith gas. And minorities are the gas reservoirs driven with elasticity andweak-water mixture driving.After analyzing accumulated factors of natural gas, it was thought that structureincluding faults is also the controlled factors of forming gas reservoirs in Bawuarea. The lithology and rock facies have big influence to the reason of the gasreservoir. That enable that a) the full of the gas reservoir is not enough, thesaturation of bound water in gas reservoir bed is generally high, so non-enoughgas layers and gas-bearing dense layers are developed. The filling of gas layers islimited. b) the gas is rich in the high location of the structure, part of lowstructure is also distributed with gas reservoir. Water of layer is mainly in lowpart of the layer and part in high location of the structure. The inversion of gasand water enable development to meet some difficulties.Through evaluating, the deep gas reservoir belongs to dense gas layer, gas and water in the same layer, water-bearing gas layer and minorities of them have gas layer with edge water, basal water. The reserve is so called difficult workable reserve, which driven energy is not itself, but comes from the manual additional energy.Relatively poor condition of reservoir lithology, belonging to basal water, edge water or water-bearing reservoirs, process engineering of gas production test of drilling, after well completion and alteration, all of these are the factors to restrict the development of difficult workable reserve.Through several years test of development, four methods of fracturing, water drainage, increasing pressure exploiting and acidification to increase recover level of difficult workable reserve. Among these four methods, the fracturing is the best one. So it is the main study method to increase recover ratio of the difficult workable reserve. New fracturing technology will be applied hardily and fracturing alteration will be performed using fully existing resources (carbon dioxide). The method of fracturing technology adapting to the deep reservoir characteristics of Bawu area have a certain economic benefit. The water drainage and increasing pressure exploitation played a certain part in increasing recover ratio, but these methods were used in the later stage of development. Acidification is not perfect in this area.
Keywords/Search Tags:Permeability
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