柴达木盆地台南气田是典型的边水驱动疏松砂岩气田,储集层非均质性强,单砂体非均质水侵现象明显.利用岩心水驱气渗流实验和数值模拟手段,研究气田开发过程中边水水侵的影响因素,包括储集层毛管力、气水粘度差、孔喉半径、采气速度和水体体积.结果显示,在均质储集层中边水水侵近似活塞驱动,在非均质储集层中,随着采气速度增大,边水容易沿高渗带形成局部突进,且自3～5倍渗透率级差开始突进明显.根据剩余气含气面积、含气饱和度、储量丰度的变化规律,将剩余气分为六种类型,剩余气富集区主要分布在未水侵气区构造高部位.边水侵入气藏后水侵区剩余气含气饱和度大幅下降,平均为33％ 左右,故适当降低配产,有利于提高采收率.

受层间非均质性等影响,多层气藏表现出层间日产气量差异大、各小层出水顺序及产水量也不相同的情况,采用常规方法无法了解每个小层的生产状况.对产气剖面测试成果在多层气藏动态分析中的应用进行了系统梳理,以台南气田F气藏为例,阐述了产气剖面可用于了解单井分层产气量及其随时间的变化、确定各小层的无阻流量、识别各小层出水顺序与出水量、分析整个气藏的分层产量贡献与剩余气分布.分析表明,通过有计划、系统地测试产气剖面,可以准确认识多层气藏的动态特征,优化确定科学的开发技术政策,提高气藏开发效果.该分析对多层气藏开发动态监测优化设计与动态分析具有借鉴意义.

Multi‐layer sandstone reservoirs occur globally and are currently in international production. The 3D characteristics of these reservoirs are too complicated to be accurately delineated by general structural‐facies‐reservoir modelling. In view of the special geological features, such as the vertical architecture of sandstone and mudstone interbeds, the lateral stable sedimentation and the strong heterogeneity of reservoir poroperm and fluid distribution, we developed a new three‐stage and six‐phase procedure for 3D characterization of multi‐layer sandstone reservoirs. The procedure comprises two‐phase structural modelling, two‐phase facies modelling and modelling of two types of reservoir properties. Using this procedure, we established models of the formation structure, sand body structure and microfacies, reservoir facies and properties including porosity, permeability and gas saturation and provided a 3D fine‐scale, systematic characterization of the Sebei multi‐layer sandstone gas field, China. This new procedure, validated by the Sebei gas field, can be applied to characterize similar multi‐layer sandstone reservoirs.

在当前情况下,应该如何应对增长下行的局面?笔者认为应从以下方面考虑: 1.目前增长下行是长期积累下来的结构失衡导致的必然结果,只有决心承受调整阵痛,尽快实现结构再平衡,才能走出下行通道.

This paper establishes the transient seepage model of the interference testing of horizontal wells under the three dimensional space.The exact real solution of the pressure at any point in the space is obtained by means of a new proposed approach and utilizing the analysis methods of modern mathematics such as the source function theory,the three dimensional characteristic value method, and the orthogonal transformation.Finally,the type curves of the horizontal well interference testing are also calculated and the effects of the observation wells’distance and the stacking way on the type curves are analyzed.The interference test type curves are divided into two flow regimes———linear flow and radial flow.The closer the position of the observation wells is the sooner the linear flow occurs,and the stacking way of the observation wells is different,and the shape of the type curve is also different.The model is quite efficient used in the study of the porous flow regime characteristics and the analysis of the interference testing of horizontal well.

Sebei NO.2 gas field I-1 layer group is shallow-buried with comparatively lower formation energy. In the process of developing, the formation pressure drops and the total energy consumption of the gas-liquid two phase pipe flowing increases gradually, which leads wellbore to produce accumulated fluid that greatly reduces gas well productivity. This paper is based on the mastery of gas field reservoir characteristics and production dynamics, analyzing the changes of gas well production performance before and after gas wells with accumulated fluid. A wellbore liquid loading identification model of Sebei NO.2 gas field is established in terms of the liquid removing capacity calculations, wellhead characteristic observation method, the pressure gradient method. In the aspect of liquid loading volume, the study based on the theory of wellbore gas-liquid two phase flow, using four classical pressure distribution models to construct a combined model that is more suitable for single wells, analyzed the features of fluid gas well distribution with structural characteristics and other aspects. Practical application shows that the analysis results are reliable and highly practical, and deepening the understanding of the phenomenon of gas liquid loading.

By researching the date of core and drilling and well logging,it was considered that the sedimentary facies,such as delta and lake facies were developed in Xiaganchaigou Formation of Nanbaxian Area.The two facies could be subdivided into distributary channel,natural barrier,inter-distributary bay,crevasse splay,underwater distributary channel,underwater inter-distibutary area,channel mouth bar,distal bar-sand sheet,delta front,predelta and shore shallow lake.Sedimentary evolution of the formation was separated into two stages.One was the lower segment(E 1 3),the other was the upper segment(E 2 3).In E 1 3 the area mainly developed shore shallow lake and distal bar-sand sheet.Sand body was at low development degree.In E 2 3,water became shallow,provenance was moved forward from northeast to south-west.Sand body is abnormally developed,delta and shore shallow lake deposit is multistage superposition.The delta front facies is especially well developed.

Gas reservoirs in the Tainan Gas Field, Qaidam Basin, are featured by shallow burial depth (833-1740 m), low diagenetic ability, loose lithology, high shale content, strong heterogeneity, and multiple gas pays with the thickness (1-3 m) of a single layer, as well as a complex distribution of gas and water. All those above will lead to great difficulties in horizontal well drilling such as trouble in the angle building, risk of borehole collapse, and the well trajectory's being out of control. In view of this, based on the case histories from more than 40 completed wells, this paper analyzes and summarizes the application of horizontal well drilling in this gas field in terms of design, operation, production performance, and so on. Also, this paper evaluates the horizontal drilling performance, characteristics of pay zones, well trajectory, drilling catching ratio, etc. According to the production status of those horizontal wells, a dynamic analysis of production, pressure, water and sand invasion was made to have an evaluation study of the production capacity and output of wells, explore the reason for water production and pressure drop, and describe the single well's yield decline features. In addition, a comprehensive comparative analysis was performed in the aspects of various reservoir types, different types of horizontal wells with diversity of lateral sections, and difference in production and investment cost between vertical and horizontal wells. In the end, the development countermeasures are presented: having better geological understandings, keeping a good grasp of well trajectory, allocating the production in a rational way, managing the on-site production effectively, having a good control of the sand and water production, and establishing a comprehensive supervision system for the supporting techniques.

As a biogenic Quaternary field with unconsolidated sandstone,Sebei gasfield is characterized by poor rock forming property,complex water-gas relationship,and easy sand and water production.Therefore,it is very necessary to have a dynamic monitoring for the field and to deepen a dynamic analysis for gas reservoirs.Combined with geological characteristics and development status,this paper presents the dynamic monitoring system and optimization that are suitable for the unconsolidated sandstone gasfield.The system meets the requirements of dynamically tracking gasfield development and production management.

Sebei gas field is featured with the characteristics of the shallow-buried gas reservoir, long gas containing well ection, multilayer gas reservoirs beds, the complicated gas/water contact distribution, the water produced obviously, sands produced frequently from the gas wells and the multi-layers gas reservoir extracted unbalancedly in the developing process. For these reasons, the paper proposed the method that interlayer interference coefficients are defined with statistical function. Combined with the data of the sand-layer's profile test, the effects of the numbers of different sand-lays, the perforated thickness, the perforated interval length and permeability contrast on the interlayer interference are evaluated and these permeability parameters are optimized.

气田多层合采纵向上的动用不均衡是由于层间干扰引起的,产生层间干扰的根本原因是压力的不均衡,引起压力的不均衡主要是储层本身性质的非均质,加之多层合采时射孔层数、射孔厚度、射孔井段等的设计欠合理,加剧了层间干扰的影响.利用统计函数定义层间干扰系数,结合砂层剖面测试数据和砂层的测井解释数据分析,是一种简单可行的评价层间干扰的方法.利用层间干扰系数和砂层剖面测试的产量,可以对气田多层合采的合理层数、射孔厚度、射孔井段长度以及不同渗透率砂层的组合进行优化.

Taking Sebei gas field as an example, this paper sorts hydrostatic pressure test data over the years and summarizes the reasons that the formation pressure drop curve generates a straight line, up-warping and recurvation from the perspective of water invasion, perforation adding, layer adjusting, sand burying, and sand control as well as inter-layer interference and inter-well interference, with typical wells analyzed and explained. On this basis, two kinds of mass balance correction models which have taken the offset of the pressure drop curve into account are proposed to calculate the dynamic reserves of gas wells with different offset shapes of pressure drop curves. Practical result shows the simple concept and strong practicality of this method, which provides an effective method for the accurate calculation of dynamic reserves of such gas reservoir.

Sebei gasfield is a very unusual Quaternary loose sandstone one in China. Due to special geological setting, its development technology and management mode are also special. In this paper, both particularity of gas production and limitation of current management mode are analyzed at first; and then, a fine management strategy of " one well one scheme " is established; thirdly, some corresponding measures are presented in terms of gas layer, wellbore and ground; fourthly, the strategy of " one well one scheme " is improved, and the management procedure and responsibility are also determined.

Abstract Sanding is a common phenomena during gas production in S gas reservoir due to the loosen sandstone formation, furthermore, the rock inner cohesion will be weaken by the water produced from interbed water and edge water, as the result, sand production in-situ is enhanced. Drawdown controlling is the reasonable strategy to sand control. To calculate the critical drawdown, a new model, which is based on the theory and lab testing data analysis to the rock composition, physical and chemical mechanism, cohesion weaken by watering, is developed in this paper. In this model, rock cohesion is considered as a function of mud content and changing with water saturation, which is a typical performance in the loose sand gas reservoir. It is more reasonable and reliable to forecast the sanding critical drawdown by this new model compare with field sanding monitoring data.

Water breakthrough is the main reason for unstable gas productivity,progressive production decrease,and industrial reserves reduction in the Sebei gas field,and this also aggravates the sanding in gas wells.Based on qualitative analysis on water sources,the layer and the source were diagnosed by a series of technical means and many different analysis methods.Thus,a numerical simulation model was built up to testify the exactness and reasonability of the above-mentioned diagnosis and analysis methods.Based on water source analysis,relative permeability curve was adjusted to fix the value of initial water saturation in the grid,the connectivity between gas and water layers,gas saturation of the boundary between gas and water layers were regulated to simulate and analysis on the water sources from gas wells in the Sebei gas field.In this way,the technology of water source identification can be improved in high accuracy so as to play an active role in preventing and controlling water breakthrough from gas wells in the Sebei gas field.

The Sebei gas field is featured by multiple layers,loose and sanding production so the production potential of the gas wells was seriously reduced. By taking advantage of dynamic data obtained from well testing,production testing,and historic production data,gas production profile,sand-producing differential pressure,as well as static logging data,a new way of establishing deliverability equation for commingling production is recommended. The new method is convenient for determining the coefficient in the deliverability equation and the absolute open flow potential by combining the theoretical formula with the empirical formula. By combining with MMBS (a performance evaluation software based on the theory of multi-zone material balance),this method can be used for both optimizing proration production and dynamic prediction. Example calculation shows that the result obtained from the newly established proration production optimization method is consistent with that of actual production thus it is significant for gas field production.

由于马北一号油田目的层段地震资料分辨率低,主体构造断层断距小,信噪比由于受断裂带的影响在平面上变化很大,原解释的断层不太落实,低序级断层无法分辨,相干分析等技术在本区不太适用,所以解决断层问题便成了本区构造解释的重点。本文旨在充分利用钻井、测井和地震相结合的方法,根据地震反射特征,结合沉积相演化规律,建立起了统一的地层划分对比标准,井震结合精细刻画构造形态和断裂系统,搞清该区断裂的发育以及空间展布规律。

Unconsolidated sandstone gas reservoir,with the developing technical problems of loose lithology,easily sanding and watering,dramatic decrease of production and the imbalance of the reserves producing degree,is a typical unconventional natural energy source in the world and thus few experience of the exploitation can be used for reference.According to the development difficulties of the Sebei gas field in Qinghai province,based on the analysis of the special laws regarding the seepage in the unconsolidated sandstone gas reservoirs and by the thorough analysis of its present developing situation,laws of development and every kind of problems encountered in the process of development,the paper has investigated some key technologies of the unconsolidated sandstone gas reservoirs in development and management which include the real-time analysis to the production performance,calculation methods to the dynamic reserves,analytical mode to the source of the produced water in the unconsolidated sandstone gas reservoirs,optimized scheme to the well allocation and couples of techniques to enhance well production under the circumstances of sanding and watering in the unconsolidated sandstone gas reservoirs,and then put forth the theoretical basis and thoughts to increase the development benefit of unconsolidated sandstone gas reservoirs at the technical management level by using gas reservoir numerical simulation to evaluate the uncertain factors in the process of gas reservoir development and the rationality of technical policies.

The heavy oil were assumed to be Bingham fluid and power law fluid in order to investigate the productivity prediction model of horizontal wells in heterogeneous heavy oil reservoirs.Based on the heterogeneous percolation theory,the well productivity prediction model was derived by assuming the heavy oil as Bingham fluid or power law fluid.This model can be used to analyze the impacts of heterogeneous factors the productivity.This model was further compared with the productivity model based on homogeneous percolation theory,and the parameters impacting the productivity were investigated.The results indicate that the heterogeneity degree has obvious impacts on the horizontal well's productivity,the more the heterogeneous,the bigger the difference in the predicted productivity lies between the new model and the model based on homogeneous percolation theory,and the model based on homogeneous percolation theory overpredicts the productivity by assuming heavy oil as Bingham fluid or power law fluid.

Recovering water drive gas reservoirs with multiple beds by multiple-zone production is an effective way to decrease production well network and number, increase single well production, prevent sand production of gas wells and realize efficient development of gas fields. But if there are no channels between the beds, the edge water advancing speed is different when multiple-zone production is conducted since the difference of the gas-water boundary and drive energy of each bed. Some single bed will have water breakthrough in advance, which causes the well production and pressure dropping greatly, even shutting-up the gas well. So, the optimization method of perforated intervals is usually used for this kind of gas fields to make the edge water advancing homogeneously in the different beds of the perforated unit, to make the gas well higher production and longer stable production period, and to improve the recovery factor of the gas field. Applying the material balance principle, the article develops a practical method for optimization of perforated intervals of gas fields. With optimizing the perforation well network and number and the longitudinal penetration of gas beds, the same or similar gas recovering rate can be obtained for the different beds in the same perforated unit, and the target of perforated intervals optimization can be achieved. The method has been applied in Sebei gas field of Qinghai province and the production of single well has been increased. Also, the method is helpful for stable production and recovery improvement of the gas field.