| This paper provides the argumentation about geology, engineering, economic and otheraspects on potential tapping with horizontal well technology in Baimiao Es3gas reservoir inDongpu depression bases on the methods including seismic interpretation, reservoirprediction, hydrocarbon detection, economic evaluation, so to optimize the well-type modeland design parameters. And on these bases, the paper gives suggestions about favorabletarget areas and wells location so to provide an important basis for improving thedevelopment effect of low permeable gas condensate reservoir. The main results andunderstanding are as follow.1. Through the study of seismic data reprocessing, sub-layer comparison, structureinterpretation and reservoir prediction, this paper indicates that the gas reservoir structurehas overall reliable and the braided channel of sublacustrine Fan has well developed duringthe deposition in Es3period which caused the sand layers lying in the channel are in goodreservoir quality. There are probably six favorable reservoir distribution areas. Meanwhile,structures and reservoir description accuracy can meet the design requirement under thecurrent data quality.2. The remaining potential of gas reservoir in lower section of Es3of Baimiao region couldbe divided into three kinds of types, which are ‘not be controlled’,‘controlled but not using’and ‘used incompletely’. Through the methods of well test analysis and dynamic reservescalculation to determine the drainage radius of gas wells, the geological reserves of ‘not becontrolled’ has been evaluated to4.97×108m3, which are mainly distributed in1,3,5sandgroups of the lower section of Es3, so to be qualified for horizontal wells drillingdevelopment.3. Regarding to Baimiao gas condensate reservoir, geological conditions and requirement ofdrilling and fracturing technique can be met with the relatively mature technology ofhorizontal drilling, trajectory tracking and geosteering, horizontal well completion, and stagefracturing technology. Among which, the sleeve bridge plug fracturing and packer orcementing sliding sleeve fracturing are the main stimulation technology for the gas reservoir.Potential tapping with horizontal wells in Baimiao gas reservoir is technologically feasible.4. Within the depth of3800-4800m (including horizontal section) range, the well economiclimit reserve in the lower section of Es3of Baimiao region is0.56-0.69×108m3. The amount under horizontal section well control reserve is more than0.8×108m3and horizontal wellscould obtain economic benefits by optimizing the design. The well reserve economic limit isclosely related to the oil and gas prices, condensate oil content, and as gas prices rises, theefficiency would be more obvious. Generally, horizontal well development in Baimiao gasreservoir is economically feasible.5. According to the geological characteristics of gas reservoirs, with the difficulty ofimplementing technology and reliability, this paper points out that stepped horizontal welltechnology could be applied to the gas reservoir horizontal well so to control two gasreservoirs in the same block or two blocks in the gas reservoir to obtain more reserves. As tothe different configuration relationship between faults and reservoir, five kinds ofdeployment model are proposed.6. Considering the heterogeneities and crustal stress distribution in the lower section of Es3of Baimiao region, this paper proposes that position of the horizontal segment in the layershould pass through the target layer to ensure the optimal reservoir control, the optimalextending orientation of horizontal wells is between120°-170°, with the segment length of600-1000m.7. On the bases of all the research in distribution of potential gas reservoir, structuralinterpretation result, reservoir distribution, physical characteristics and economic limit,5target areas are optimized chosen and two horizontal wells are proposed, and they all haveachieved good implementation effect. |
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