Sichuan Basin and Ordos Basin are classic depositional basins in Central China,and constitute the orogeny-basin pattern with Qinling orogenic zone.The evolution of Tethys Ocean is the main drive of the mechanism.During Indosinian and Yanshan movement age,the obduction zone of Helan mountain in western Ordos margin basin and organic zone of Longmen Mountain formed,the thrusting and uplifting zone was formed by Qinqi orogenic zone,which caused the formation of foreland basins,and the frame of orogeny-basin was composed.The formation of the foreland basin is consisted of three stages:foreland depression basin formation stage,intracontinental foreland basin formation stage and regeneration foreland basin formation stage.The central foreland basin was continental collision orogenic belts and peripheral foreland basins.The orogeny and basin formation had same kinematics process and dynamic mechanism,and the orogenic belts controlled the formation process of the foreland basin.
The area within Feiyantan oilfield was under polymer injection when the total water cut reached 86.1%. As such the area claims the lowest water cut among all the areas put into polymer injection in Shengli oilfield so far. A good effect of increased oil production and decreased water cut appears after thepolymer flooding has been carried out over one year. Oil production increases from 652 t/d to 758 t/d, while total water cut decreases from 86.1% to 79.9%. And a cumulative incremental production of 2. 2×104t has been obtained. Currently the character of early-stage flooding-production performance is apparent. The practiceand research show that the important measures to improve polymer-flooding effect in the coming years should be differential management of the injection-production wells, and a balanced recovery of liquids from the wells.
According to the definition of all-frequency band, a simple formula for measuring and calculating all-frequency band is derived in this paper, i.e. △f=fo/Q and △f=R/2πL. The former is used for measurement and the latter for calculation. The error obtained is smaller than that by the general method.
In order to clearly understand the characteristics of the vertical fracturing wells and multiple laterals horizontal wells in coal bed methane production,based on well drilling and completion,the measures and principles increasing production,in this paper,the production mechanism of two kinds of coal bed methane wells is stated.Based on the flowing characteristic of groundwater and well drilling and completion,combined with Darcy′s laws,the changing pressure models of two kinds of wells are gained.According to the supplying ability and primary task in every drainage stage,the working system in saturated water is divided into adjust process and steady falling liquid depth process,the working system in two-phases stream stage is divided into four processes,i.e.,adapt process of working system,steady falling pressure at the bottom of the well,steady production process and controlling pressure at the bottom of the well and production process.Finally,it is pointed out that attendant proceedings in the process of the well drilling and completion and production,these acquaintanceship is of guidance to the production of coal bed methane wells.
The 91 layer，segment 2 of Shahejie Formation，Tuo 7 fault block，Shengtuo Oilfield is taken as an example，3D spatial distribution stochastic modeling of the interlayers is studied in order to find the relationship between interlayers distribution and remaining oil distribution.On the basis of geologic setting，an integrated study is conducted，with well drilling data and logging.Three interlayers types which include muddy interlayer，calcareous interlayer and physical property interlayer are confirmed.A 3D distribution modeling for interlayer is developed by sequential indicator simulation method.The model analysis reveals the distribution range of calcareous interlayer is the greatest，the distribution range of muddy interlayer is in the middle.The average thickness of muddy inter layers is 0.6m，the extending distance is 50-105m，and the distribution area is 0.01-0.05km 2.Interlayer distribution density is 0.11-0.63m/m，distribution frequency is 0.52-1.24layers/m.The average thickness of calcareous interlayers is 0.4m，the extending distance is 40-180m，and the distribution area is 0.01-0.08km2.Interlayer distribution density is 0.15-0.76m/m，distribution frequency is 0.61-1.39layers/m.There are many interlayers in 2-163，3-33，5-228，4-10，7-221，5-213 well areas，where
remaining oil could be rich.
As the cement slurry hydration speed is slow and curing time is relatively longer under the condition of low-temperature,it is easy to result in oil,gas and water invasion which leads to poor well cementation quality,and the early strength agent without chloride is lack in cementing of low temperatrue shallow formation.In order to cope with these situations,based on the principles of hydration and low temperature high early strength of cement slurry，the water-soluble chlorine-free chemical raw material，which has the function of low temperature high early strength on cement,is adopted in this research.According to experiment,two kinds of inorganics materials A and B,an organic salt C and an organic acid are selected out and ZC-2S which is a new kind of low temperature early strength accelerator without chloride is developed.ZC-2S can prominently accelerate early strength of general density/low density cement slurry and is of good compatibility with other cement additives.ZC-2S is good early strength accelerator used in low temperature shallow formation and can cement in absence of dry-mixing equipment.
The contradiction between improving gas field production rate and controlling formation sand production has become the one of the main problems which restain the gas field exploitation in loose sandstone.To gas well testing and exploiting,it is of important significance that the critical production pressure difference of gas formation sand production is precisely predicted,which is taken as the one of important factors of gas well allocation.The mechanism of sand production in loose sandstone gas field is analyzed in detail,well logging data is used to calculate lithologic mechanics parameters,and also,MohrCoulomb destroyment criterion is used to calculate critical production pressure diffrence of gas well sand production.By comparing the productional sand production pressure diffrence of several wells in S gas field with the calculated critical sand production pressure diffrence,it is found that there is a quite promise coinsidence,which suggests that the method is reasonable and is meaningful for determing reasonable production pressure difference in loose sandstone gas field.
Gongga mountain area has developed 71 glaciers, five of which are longer than 5 kilometers, Hai Luo ditch glacier is the largest in scale and the lowest in elevation in Gongga mountain area. According to its distribution, shape and scale, theglacier is a mountain glacier. But it belongs to the dynamic metamorphic glacier by its origih.Hai Luo ditch glacier formed about 1600 years ago on the east edge of Qinghai-Xizang plateau In its longitudinal direction, neve basin stands above, but glacier tongue stretches low. Between them the peculiar big high- hanging glacier cascades connect with each other.The formation and existence of glaciers were mainly concerned with the orogenic movement in recent periods，and with the geological background of north-southern tectonic mountain system of Gongga mountain，the natural regional geographical environment，the north-southern Hengduan mountain system in the south and the influence of southeastern seasonal wind on the southern sea region.Hai Luo ditch glacier is now in the strong melting and flinehing period，which is concerned with regional climate oscilation changes within scores of years，and in not concerned with“Greenhouse effect”.The scenes of the glacier don’t disappear in the predictable period because of flinching.
In the course of thermal heavy oil recovery,calculating on-way parameters and evaluating bottom hole parameters through injection wellbore are generally based on the ordinary steam.However,as overheated steam is single-phase gas,heat loss calculation model for ordinary wet steam is not applicable.On the basis of conservation of mass,conservation of momentum,conservation of energy,with the introduction of the PVT data sets,the new on-way parameter calculation model through injection wellbore is set up.On-way overheated steam parameters under various conditions are obtained by programming.As the results showed,as the well depth increases,the temperature and the pressure of overheated steam varies greatly,the increase of injection temperature does not obviously impact the on-way heat loss.
By meas of sequence stratigraphy and analysis method based on base level cycle，the data of well drilling，logging，2D and 3D seismic survey are comprehensively
analyzed，three boundaries in Huoshaogou Formation and Baiyanghe Formation of Tertiary，Shida Sag，Jiuquan Basin are identified，which are classified as one suppper long
term base level cycle(the 2ndlevel sequence) SLSC1 and two longterm base level cycle(the 3ndlevel sequence) LSC1 and LSC2.It is pointed out that in Tertiary
SLSC1 of Shida Sag，there are well developed alluvial fan sedimentary system，braided river sedimentary system and shallow lacustrine sedimentary system.Constrained by
isotime stratigraphic framework，the internal relationship between base level cycle and the development law and distribution feature of reservoir rocks，cap rocks and
reservoircap association is analyzed in detail，it is also pointed out that there is huge exploration potential in Tertiary in the area，the favorable reservoir area
are the ones located in middle alluvial fan and the fan margin braided channels in LSC1 base level semirising cycle，as well as in braided channels in LSC2 base level
semirising cycle，laterally，the structural and lithological association reservoirs in middle alluvial fan and alluvial fan margin in the north of Bainan well 5，south
of Dan well 7 and the west of Bainan well 2，as well as the lithological reservoirs developed in the setting of structure are favorable area for hydrocarbon exploration.
The introduction of viscoelastic surfactant (VES) , or clear fracturing fluids (ClearFRAC fluid) , which is capable of eliminating polymer damage while enhancing conductivity of proppant packs , has changed the way of proppant transport by traditional polymer fracturing fluids. The paper has summed upand reviewed systems of present hydraulic fracturing fluid at home and their shortcomings , and summarized the development , the theory basis and cases of successful fracturing treatments of ClearFRAC fluid in abroad. Field results have shown that the performances of the ClearFRAC fluid are better thanpolymer fracturing fluid , which are high effective and nonOdamages over conventional polymer fluid systems. Some comments on the studies of ClearFRAC fluid in our country have been giv2 en in this paper.
In order to determine the period of hydrocarbon accumulation in Linnan Sag，study on fluid inclusions of different structural parts is done systematically in this paper.The history of hydrocarbon migration and accumulation in Linnan sag is discussed based on the data of fluid inclusions，homogenization temperature，burial history，thermal history and hydrocarbon generation analyses.There are mainly 3 types of fluid inclusions in sandstone reservoirs in Linnan Sag，i.e.，aqueous inclusion，liquid hydrocarbon inclusion and gas hydrocarbon inclusion.The homogenization temperatures of the aqueous inclusions coexisting with organic inclusions are 105-125℃.It is supposed that in different structural parts in Linnan Sag there are different periods of hydrocarbon accumulation.Hydrocarbon accumulation in the center of Linnan Sag occurred in two stages.They were late Oligocene Dongying Period and Miocene Guantao Period to Pliocene Minghuazhen Period.The latter is the main accumulation period.Hydrocarbon accumulation on the edge of Linnan Sag occurred in Miocene Guantao to Pliocene Minghuazhen Period.
