Erlian basin underwent a complex development history in Mesozoic and is a multi-folded basin system. It was once a little-scale rift-subsidence basin in early-mid Jurassic, a structural reversal basin in late Jurassic (accompanying strong volcanism), a lager-scale rift subsidence basin in early cretaceous and a structural reversal basin in late of early cretaceous. The region has been in a wholly lifting state since late cretaceous.
Sand beds from the t2k1in middle part of the second district in kelamayi oil filed was selected. Static alkali consumption tests were completed at different temperatures (30c, 50c) and solid/liquid ratios 1/2(g/ml), 1/5(g/ml (1/10(g/ml) for 8hours, 120 hours and 360 hours respectively. Absolute alkali onsumption was calculated for each test. Results show absolute alkali consumption increases while temperature goes up and solid/ liquid ratio decreases. Absolute alkali consumption for sands in NaOH solution is much lager than that in Na2CO3. But the relationship between absolute alkali consumption and alkali, temperature and reaction time will be affected by solid/liquid ratios.
Distribution of the pore and throat of reservoir is important content in reservoir study. Through capillary pressure curve study of sand stone reservoir in beisheng area, tuha oilfield, a new approach to establish reservoir pore and throat volume distribution is put forward. The model will be helpful to solve the problem resulted from lacking of mercury injection samples or core data in reservoir pore structure, and correctly evaluate the heterogeneity of reservoir pore structure in the area.
This paper shows the effect of steam flooding on pore structure and reservoir minerals in Lian-hua reservoir of Liaohe Gaosheng oil field based on lab simulation and core analysis.The pore structure of reservoir media are studied to compare with heat simulation experiments. Steam flooding will lead to the increase of porosity and pore diameter, and the decrease of pore throat and permeability. Thus, the heterogeneity of pore structure becomes more serious .Steam has strong effect on the microstructure of the clay minerals . The experimental tests prove that new minerals, such as smectite and zeolite, will be formed at 250℃. However, the heavy oil can easily carry fine particles(<4μm) ,and finally the content of smectite in reservoir will decline .The main factors of formation damage during the steam flooding are particle migration and swell of smectite.
Cheng-hua slope oil field is located in the south of the shan gan ning basin, the braided and meandering river deposition of yan-an formation is overlying on the old erosion surface of yan-chang formation, the area is characterized by apparent mark layers and recycle, main pay zones areY8-Y10members. The relation between the distribution of prosity and permeability and sedimentary micro-facies, classifications of reservoir and relations between pore structure characteristic and physical property are mainly discussed in the paper.
Well Kong 3 is located in Kong buried ancient mountain structure in dagang exploration region, research shows that oil in the well is from source rocks of Ordovician, geochemical analysis indicates that the average organic carbon of Ordovician limestone is 0.14%, chloric bitumen A is 0.11%, total hydro carbon is 57.6 ppm, which means bottom limits of organic rich ness of source rock have been reached, and data from some rocks have been ranked in good to relatively good range. The kerogen is mainly typeⅡ1,Ⅰ1andⅡ2, most of organic samples belongs to matured to highly matured evolution. This shows an important significance for exploration of primitive reservoir in dagong region.
Prediction of depth between wells is a key issue in micros-structure study. The seismic data can not predict the depth of formation with a thickness of 15 meters or less, but the fractal theory can be successfully applies. The process to fulfill predicting parameter between wells include: trend surface analysis of the depth; calculation the fractional dimension H ; calculation of the residual error of every point and prediction of the value by trend value combining residual error. The result of predicting the thickness of DJL reservoir has verified the validity of the method. Drilling data indicates that’s microstructure map plotted with the method can effectively predict the distribution of residual oil.
On the foundation of thin- section identification, cast analysis, special seismic treatment and experience data, this paper studies the characteristics of Ordovician reservoir in east upwarding and vicinity in liaohe basin, the contents include the lithologic characteristics, reservoir space types, porethroat structure and physical property. The authors conduct the further probe on the major factors, which control reservoir formation. The favorable factors include dolomizatopn and segmentation. In the end, authors point out Ordovician crust of weathering will be the important target in the further exploration.
According to NMR and capillary pressure data, combining jizhong geologic and well test data, well logging interpretation technique is put forward for low resistively reservoir under the condition of complicated geology and reservoir irritable water saturation test method based on NMR logging. By two years application in northern china oil field, the technique can easily and quantitatively evaluate low resistively reservoir resulted from high irritable water saturation, a satisfactory result is achieved.
We must find out the accurate distances to faults at first to determine where we can drill nearby reservoir faults. But among all the modern well test interpretation models, the distances to faults are obtained based on approximate mirror reflection theory which usually brings bigger error. However, we can solve this problem by precise mirror reflection model presented in this paper. The field case study proved that the curve matching based on precise mirror reflection model is much better, the distances to faults more accurate which are very useful to oil field development. The results must be revised if approximate mirror reflection model are applied.
In the development plan making of oilfield, production forecast ties up to the success of reservoir development. It determines the developing scale and investment, and plays an important role in improving the developing efficiency and operation performance. There are many kinds of methods to forecast the production of oilfield, such as decline curve method, neural network method, and Poisson distribution method, etc. The key point to use all these methods is parameter estimation. The widely used methods are trial solution and the least square method. They need huge calculations and their results are less reliable. A new kind of intelligent genetic algorithm was employed to get the optimal parameter. Using it in the model has proved its reliability for production forecast of oilfield.
Pressure drops in horizontal wellbore influence production performance greatly. This paper analysis the property of horizontal wellbore single-phase variable mass flow coupled with flow in reservoir when a horizontal well is producing. The basic equation are derived to calculate the pressure drops of the flow within an open-hole and a perforated completion horizontals well bore based on the principle of conservation of mass and momentum. And the equation of flow in the reservoir is also derived using potential superposition principles. Based on this, a new model to calculate pressure drops in horizontal wellbore is developed. The results of the practical calculations are shown.
In order to use well test information correctly, a theoretical study was conducted on the determination of productivity index(PI) and formation pressure from IPR curves. For pressure maintaining reservoir, because the external boundary pressure (Pe) keeps constant and the average pressure is a variable over the drainage area of the well, only Peand the productivity index Jo(Pe) of an oil well defined by Pecan be obtained from IPR curve. For depleting reservoir, because Peis a variable and the average pressure over the drainage are a keeps constant, only and the productivity index Jo(P) of an oil well defined by can be obtained from IPR curve.
Combining reservoir engineering method and numerical simulation technology, accounting for the non-Newtonian behavior of fracturing fluid and the 2 dimensional flow of filtrate during fracturing operation, a 2D dynamic leak off model of non-Newtonian fracturing fluid was established. Numerical method was employed to solve this model and the simulation results were compared to that of 1D model. It shows that, the leak off rate calculated at the consideration of that fracturing fluid leak off flows in the direction that perpendicular to the fracture face is smaller than that of 2D flow, and their difference increases with formation permeability. The 2D model is more reasonable. Because the non-Newtonian behavior of fracturing fluid and the 2D flow were accounted, this model is more applicable and its simulation results are closer to field. It can reduce the fracturing operation venture and increase the reliability of fracturing design.
The basic methods of 2D, 3D finite- element thermal models created and meshed have been introduced in the paper. Simulating fluid-flow field with thermal field, the materials of well hole and perforated tunnel are simulated by the same conductivity material, the thermal conductivity is infinitely great with respect to the conductivity of formation, it can simulate the fluid-flow field of the whole perforated completion. The 2D and 3D models can be used to study the velocity in the perforated tunnel, the fluid - flow velocity of out boundary of crushed zone, fluid-flow pressure field, the flow rate of whole size well and the production rate, with or without drilling dam age and crushed zone. A general program of the meshed models has been written with APDL computer language. it provides practical FEM meshed models for the optimal design and production rate prediction of perforated completion, and also provides a brief method for the research area.
