In the traditional well test models, the quadratic gradient term of nonlinear partial differential equation was neglected according to the assumption of slightly compressible fluid, which could lead to error when the well test time was too long. As time went by, the fluid flowing boundary of low permeability reservoirs extended outwards continuously. In order to study the flowing law of low permeability reservoirs with deformed media, the flow model of low permeability reservoirs of deformed media was built, which considered the influence of starting pressure gradient, moving boundary and quadratic gradient term. The numerical solution of the flow model was obtained by the fully implicit finite difference method. The pressure dynamic curves were drawn to analyse the seepage law of different starting pressure gradient, deformed media and moving boundary. The influence of the quadratic gradient term on the pressure dynamic curves was analyzed. The results could help people understand the seepage mechanism of low permeability reservoirs and provide the theoretical basis for exploring the low permeability reservoirs.
The C oilfield is located in the Bohai Bay Basin, a typical strong bottom water reservoir. Oilfield reservoir and oil–water distribution are complex. At present, the C oilfield has entered the high water cut development stage, and it is challenging to stabilize oil and control water. The reservoir with an imperfect well pattern has dominant bottom water ridge channels, uneven oil–water interface uplift, limited water drive sweep range, and low inter-well reservoir production degree. The oil layer between the horizontal section of the production well and the top of the reservoir cannot be effectively developed, and the remaining oil is enriched. Therefore, it is urgent to explore new energy supplement methods to improve inter-well and vertical remaining oil production in the C oilfield. In this study, the displacement medium is optimized through indoor experimental simulation. From the experimental results, the remaining oil between the sand bodies can be used in heavy oil reservoirs, and the residual oil between wells can be significantly utilized in the alternate displacement of gas and foam, and the recovery degree of the reservoir is increased by 12.44%. The remaining oil at the top of the reservoir can be used in the upper reservoir to increase the remaining oil in the top of the reservoir by injecting gas and foam alternately in the new reservoir. The final recovery of the reservoir is increased by 6.00%. This experimental study guides tapping the potential of the remaining oil in the offshore strong bottom water reservoir.
In order to study the profile control characteristics of emulsions in porous medium, the heterogeneous experimental model was established, by which the experimental scheme was designed with different permeabilities, matching degree of particle size and concentration of emulsions. Based on experimental results of physical simulation, the concept of distributing rate and changing coefficient was introduced to quantitatively evaluate the profile control characteristics of emulsions. The results of the study show that, as the permeability ratio and emulsion concentration increase, the profile control characteristics of emulsions will enhance. The profile control characteristics of emulsions will be the best. The profile control scheme with emulsions was implemented in Bohai X oil field, The research results can be used for reference to design the profile control scheme in Bohai heterogeneous reservoir.
We introduce the notion of product systems over quasi-lattice ordered groupoids, and characterize the co-universal algebras for compactly aligned product systems over quasi-lattice ordered groupoids by using the C * -envelopes of the cosystems associated with the product systems.2010 Mathematics Subject Classification. 46L05. Key words and phrases. Co-universal C * -algebras; Product systems; Quasi-lattice ordered groupoids.
The third Member of Dongying Formation reservoir in CFD oilfield is steep slope fan-delta deposits; it was penetrated by 6 wells, each well belongs to different fan body. 143 meters oil reservoir was found in well 1, the lithologic combination are complex pebbly sandstone and sandstone with undeveloped interlayer. The reservoir feature is low porosity and low permeability, large thickness with quick lateral variance, and strong internal heterogeneity, which made reservoir characterization challenging. Firstly, high resolution sequence stratigraphic framework of the third Member of Dongying Formation reservoir was established by using of core, log and seismic data, guided by sequence stratigraphy and sedimentology. Then, microfacies classification scheme was determined by actual data and the depositional model. The spatial distribution regularity of fan delta and its microfacies was researched by seismic sedimentology attribute slice and sedimentary numerical simulation. Combined with rock composition features, physical properties, diagenetic characteristics, etc., reservoir classification evaluation was researched. Lastly, a geological model was established for quantitative prediction of the 3d distribution and physical distribution of each reservoir type. The third Member of Dongying Formation reservoir of well 1 block was divided into Lowstand Systems Tract and Transgressive Systems Tract, subdivided into six subsequence sets and 11 subsequences. Good reservoir was mainly distributed in the upper subsequences of Transgressive Systems Tract. Through fine seismic explanation, the plane distribution of each subsequence was determined. The fan delta was divided into six microfacies, including main channel, sheetflood sand beach, braided channel, overflow sand beach, sheet sand and lacustrine mudstone. Middle-fine sandstone and well sorted pebbly coarse sandstone in braided channel and main channel are good reservoir. Based on seismic sedimentology, different strata slicing schemes were used to extract seismic attributes for spatial distribution prediction of good reservoir. Together with sedimentary numerical simulation, the planar distribution and vertical evolution of fan delta and its microfacies were researched, then fan delta sedimentary model of good reservoir developed and Transgressive Systems Tract was established. Based on the study above, the reservoir was divided into four types with different physical characteristics. Then reservoir distribution and physical property distribution of all types were quantitatively predicted by geological modeling. Lastly, a more accurate geological model was provided for oilfield development plan design. Geological model of CFD oilfield was established by comprehensive application of sequence stratigraphy, seismic sedimentology and sedimentary numerical simulation. The modeling method adequately simulated the reservoir heterogeneity and fluid flow characteristics of complex fan delta reservoir with sparse wells in oilfield development plan design stage. The method will be used to guide the fine characterization of more similar oilfields in Bohai Bay Basin.
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