基于岩心、薄片、地震、测井等资料,通过分析伊朗A油田白垩系Sarvak组生物碎屑灰岩储层内发育的隔夹层类型、地质特征及井震响应特征,系统研究了隔夹层的成因及展布特征.研究表明:A油田Sarvak组储层主要发育泥粒灰岩隔夹层和粒泥灰岩隔夹层,根据隔夹层发育的主控因素,可划分为沉积成因、成岩成因和复合成因.Sarvak组储层内隔夹层的展布特征具有明显的规律:厚度较大、广泛发育的隔夹层主要受沉积作用控制,沉积环境以局限台地相和潟湖相为主;厚度较薄、局部发育的隔夹层主要受压实作用和胶结作用等成岩作用控制.Sar2和Sar7段发育沉积成因隔夹层,平均厚度分别为15 m和5 m;Sar3和Sar8段局部发育成岩成因隔夹层,平均厚度分别为3.25 m和4.5 m左右;Sar4—Sar6段发育大量的复合成因隔夹层,厚度变化较大,总平均厚度为4.8～7.1 m,纵向上广泛发育.

Even if all of them are carbonate platform deposits, their sedimentary models and types and characteristics of microfacies are different. This study aimed to establish a sedimentary model for the rimmed shelf-type carbonate platform with large tidal channel, divide the types of facies, describe the spatial distribution of facies, and analyze the internal structural characteristics and evolution of facies. This paper takes a giant massive carbonate reservoir of A oilfield in the Middle East as the research object, discriminates the sedimentary environment and identifies the facies to establish the sedimentary model through the establishment of sequence framework based on multiple geological information. Under the guidance of the model, through seismic multi-attributes analysis, cores and logs combination and 2D&3D seismic jointed, the vertical stacking and lateral distribution of the sedimentary microfacies, the boundary, trend and evolution of tidal channels, and the internal characteristics and the high quality reservoir of microfacies are characterized. The study confirms the sedimentary model of the carbonate reservoir in A oilfield as a rimmed shelf-type carbonate platform with large tidal channel in the highstand systems tract with six third-order reverse cycles, which mainly develops 4 subfacies including 6 microfacies: platform edge shallow shoal, intershoal, open platform, point shoal, restricted platform and tidal channel. The tidal channels include two types, which are east-west or south-eastward and gradually develop from south to north, from bottom to top. High quality reservoir mainly developed in the platform edge shallow shoal and the deep complex tidal channels. Multi-information comprehensive analysis reduces the uncertainty of facies, the spatial distribution of microfacies and characterization of high-quality reservoirs provide a basis for development plan design and well location deployment.

The S formation of oilfield A is a giant massive carbonate reservoir with edge and bottom water and strati-form features, strong heterogeneity, complex internal characteristics and undeveloped faults. Within 470 km2, there are only 2 existed wells and 10 2D seismic lines control most of the area. How to use all kinds of information to enhance geological understanding and control the whole modeling process is the key. Based on various geological data and information, depositional model is established as a conceptual guide. The pseudo-3D inversion volume is established by well-seismic combination and 2D and 3D joint and with the optimal geo-statistical algorithm and used to constrain the geo-modeling. Under the guidance of geological knowledge, the pseudo wells are designed to increase the control point for reducing the randomness of the geo-modeling. The idea of hierarchical facies-controlled modeling from sedimentary facies, lithofacies to property models is adopted in order to improve the consistency between the model and geological knowledge. In the whole modeling process, the variogram models are established by using the combination of lateral prediction of seismic data and vertical prediction of well data. The geological model has effectively guided the design and implementation of the development program. The Net-pay of horizontal well is over 90

The carbonate reservoir space types and heterogeneity features, which influence the development of oil field, are comprehensively analyzed, taking carbonate reservoir in Sarvak Formation of Iranian Azadegan oil field as a case study. The rock types of Sarvak Formation are mainly composed of bioclastic grainstone, and the secondary dissolution porosity dominates the reservoir space, with reservoir permeability greatly improved by fractures. The relationship between porosity and permeability, dynamic production tests, and the MDT tests demonstrate that the vertical interbed heterogeneity and planar heterogeneity apparently exist in the carbonate reservoir of Sarvak Formation. The migration of high energy banks that developed on the gentle slope platform margin during Cretaceous Period formed the major part of favorable reservoir of Sarvak Formation. The development of carbonate reservoir is controlled by many factors, such as high frequency sea level change cycles, epidiagenesis that happened along the sequence boundaries, the faults and fracture developmental zones caused by later tectonic activities, as well as the hydrothermal dissolution that occurred along the faults. Sar-3 member and Sar-8 member are corresponded to the top parts of shallower upward cycle of third-order sequences, developing high energy grain banks. Concurrently, their locations near the sequence boundaries are easily exposed and dissoluble, with most developed reservoirs.

The bioclastic limestone reservoirs of Cretaceous period occupy an important position in the petroleum industry of Middle East. It is the carbonate heterogeneity that is challenging the accuracy of the reservoir prediction, which brings forward higher requirements for the seismic data quality. Besides, some seismic data are processed more than 10 years ago, the signal to noise ratio (SNR) is relative low due to the random noise and coherent noise like acquisition footprint anomalies. The acquisition footprint artifacts caused by acquisition and processing seriously suppress the true stratigraphic features, which can result in pitfalls in seismic interpretation, seismic attribute analysis as well as seismic inversion. While the pre-stack seismic data is usually unavailable, which means that the noise can hardly be subtracted by conventional pre-stack seismic processing workflows, such as statics, high-resolution velocity analysis and ground roll attenuation. Consequently, a comprehensive post-stack seismic data conditioning workflow is necessary to solve the above problems. In order to improve the post-stack seismic data quality, a comprehensive data conditioning workflow are applied for noise suppression. Firstly, structural-oriented filtering is utilized to attenuate random noise and partial acquisition footprint artifacts. Then 2D waveform transform of seismic amplitude and filtered seismic attribute in x-y domain are calculated, to separate acquisition footprint anomalies (large wave number in kx-ky domain) from true structural signal (small wave number in kx-ky domain) by interactive analysis. The application of Laplace-Gaussian (LoG) filter deserves an obvious improvement in acquisition footprint suppression workflow. The comprehensive noise attenuation workflow in this paper can effectively remove both periodic and non-periodic noise to obtain higher signal to noise ratio (SNR) for post-stack seismic volume. In this way, the stratigraphic features (tidal-channel, reef-beach complex) can be more clearly depicted and some artifacts caused by noise will disappear in seismic attribute calculation, seismic inversion and reservoir prediction.

中东地区大型油气藏多属于海相碳酸盐岩油气藏,其中白垩系生物碎屑灰岩油藏占据主要地位.地震数据中的采集脚印会对地震解释、属性分析、储层预测造成较大影响.采集脚印可以通过叠前地震数据处理流程消除,但处理流程用时较长且过程繁琐.利用采集脚印对地震属性的敏感特性,在二维波数域中将有效地质信号与采集脚印分离,并应用拉普拉斯高斯滤波器,实现了自适应去除采集脚印.通过压制采集脚印,提高了地震数据信噪比,为中东地区陆上大型生物碎屑灰岩油藏地震属性分析和储层预测提供了技术支撑.

Bioclastic limestone reservoir is playing a dominant role in the petroleum industry of Middle East. The oilfield in this paper belongs to long-axis asymmetric anticline. The S formation of Cretaceous period universally developed bioclastic limestone of carbonate platform system. It is the reservoir heterogeneity that severely limits the oilfield development. We firstly analyze the lithofacies based on the core and thin section. Then the detailed well and seismic interpretation illustrate the sequence stratigraphy and facies analysis, and tectonic evolution are analyzed to restore sedimentary procedure from Palaeocene to late Pliocene stage. Ultimately, high quality reservoir of bioclastic limestone are depicted according to comprehensive analysis. This paper offers reference and inspiration for bioclastic limestone reservoir: reef-beach complex and sweet spots in tidal-channel are dominant reservoirs for bioclastic limestone of Middle East.

In order to avoid asphaltene precipitation caused by gas injection for enhance d oil recovery , the asphaltene onset pressure (AOP) was tested in the laboratory .On the basis of the analysis of the as‐phaltene precipitation mechanism during gas injection ,the asphaltene onset pressures under different tem‐peratures were measured along with crude oil samples in the process of high‐pressure gas injection ,by using the self‐developed laser solid detection system and the light transmission method ,so as to determine the depth of asphaltene precipitation .T he results demonstrated that the asphaltene onset pressure decreases with the increase of temperature ,AOP are 44.1 MPa ,39.7 MPa and 35.2 MPa at the temperatures of 44 ℃ , 80 ℃ and 123 ℃ respectively in the experiment ;the asphaltene onset pressure increases 0.5 0.6 MPa w hen a‐mount of substance fraction 1% of hydrocarbon gas is injected .According to the asphaltene deposition en‐velope and wellbore temperature‐pressure curve ,it is predicted that asphaltene precipitates at a depth of 1 800 m ,which matched the field conditions very well .The study suggested that there is a linear correlation between the volume of gas injection and the asphaltene onset pressure ,which could provide a theoretical basis for preventing and removing asphaltene precipitate in gas injection on site .

Production pattern of oil wells and influential factors on productivity for the massive carbonate reservoir in the Middle East were researched by productivity evaluation on Sarvak and analysis of properties impact on production. Based on dynamic performance of Sarvak production test, the relationship between daily oil production, tubing pressure, cumulative oil production and choke size was analyzed and reasonable productivity prediction model was established by applying Poettman model, and the effect of physical properties and fluid parameters on productivity were analyzed further by numerical simulation. The study shows that daily oil production is linearly correlated with oil pressure under certain working regime, and daily oil production is power law correlated with choke sizes before and after working regime adjustment. The average designed single well productivity should be about 270 m(3)/d by depletion to ensure a three-year plateau period. Sarvak is a blocky carbonate reservoir, when developed with horizontal wells, interbeds distributed between layers and permeability property have the strongest impact on production of horizontal wells. So, highly deviated wells should be used to reduce the effect of interbeds and acidizing should be considered to improve the reservoir physical properties.

This paper, taking lacustrine carbonate rocks of Guanzhuang Group of Pingyi Basin for example, aims at studying the paleogeographic significance of lacustrine carbonate rocks. Taking the sedimentary theory as guiding theory and based on the outcrop section,we analyze the formation and sedi- mentary features of Guangzhuang Group. Combined with the formation and evolution of the basin, we also analyze the conditions of sedimentary environ- ment, such as the paleontology, ancient climate, content sources, physical and chemical conditions of water medium, and so on, and clarify the paleogeo- graphic patterns and characteristics when Gaanzhuang Group was deposited. The study suggests that the basin was a warm inland environment when lacus- trine carbonate rocks were deposited. And the tectonic movement was relatively static, paleotopography was relatively flat, which was favorable to the deposi- tion of the lacustrine carbonate rocks, and carbonate concentration in the environment of shallow water, low and middle energy,little terrigenous fragmental materials. Thus it is demonstrated that the favorable paleogeographic setting for lacustrine carbonate strata was the sedimentary environment with relatively static tectonic movement, flat terrain, shallow water and low energy.

Great Unity Oilfield,one of the main productive ares of Sudan 1/2/4 project,lies on the central uplift belt in Muglad Basin.Structure of Great Unity is a large-scale faulted anticline,with 3 trap patterns developing on it,i.e.,anticline,fault-nose and fault-block.The Great Unity structure has large amount of traps with 29 structural traps on top Aradeiba A.Abu Gabra formation source rock and multiple sets of reservoirs including Bentiu,Aradeiba,Zarqa,Ghazal and Baraka,etc,form the multi-oil-water system called "tacked plate pattern"reservoirs which have many oil-bearing formations and long oil-bearing well sections.Most are layered reservoirs.Analysis of key factors of reservoir accumulation indicated that the major faults are the vertical migration pathways of hydrocarbons.Oil and gas accumulated along the major faults.The lateral sealing condition was crucial to form an effective fault-block trap.

Temperature and pressure are two main factors that affected aqueous phase change in natural gas. While gas flow from reservoir to ground, there will have two flow process. One is isothermal seepage and pressure release, the other is temperature drop and pressure release. In the both course of production, the occurrence of water evaporation and condensation would be appeared. Analysis showed that water evaporation just only happened in the isothermal process of pressure release and that water evaporation and condensation appeared in the process of temperature and pressure release. Through the analysis of the aqueous phase changes, production of condensate liquid was calculated and its change with the temperature and pressure was analyzed. Based on the amount and the features of condensate water, the source of production water could easily be determined. This study has certain significance for the development of natural gas.

Temperature and pressure are two main factors that affected aqueous phase change in natural gas. While gas flow from reservoir to ground, there will have two flow process. One is isothermal seepage and pressure release, the other is temperature drop and pressure release. In the both course of production, the occurrence of water evaporation and condensation would be appeared. Analysis showed that water evaporation just only happened in the isothermal process of pressure release and that water evaporation and condensation appeared in the process of temperature and pressure release. Through the analysis of the aqueous phase changes, production of condensate liquid was calculated and its change with the temperature and pressure was analyzed. Based on the amount and the features of condensate water, the source of production water could easily be determined. This study has certain significance for the development of natural gas.