Diagnostic Method and Adaptability Analysis of Multiple Water Breakthroughs in Horizontal Well in Combined Well Pattern

The combined well pattern has been widely used in reservoir development, with a common pattern being a horizontal well in the center for oil production and multiple vertical wells around for water injection. For this type of well pattern, determining the horizontal well is affected by which injection wells, especially when the injecting water breaks through, accurately determining the direction of water inflow will provide an important basis for targeted water well measures. Based on the production performance data of horizontal wells, the semi logarithmic relationship curves of water-oil ratio, derivative water-oil ratio, and cumulative production were used for the first time to determine the breakthrough problem of water injection in the surrounding water injection wells of horizontal wells based on their response characteristics. The adaptability of this method under different influencing factors was analyzed. Introducing the parameter of cumulative production not only preserves the variation trend of the derivative of water-oil ratio with time, but also facilitates the processing of actual production data.

A novel method for predicting breakthrough time of horizontal wells in bottom water reservoirs

Dimensional analysis and numerical simulations were carried out to research prediction method of breakthrough time of horizontal wells in bottom water reservoir. Four dimensionless independent variables and dimensionless time were derived from 10 influencing factors of the problem by using dimensional analysis. Simulations of horizontal well in reservoir with bottom water were run to find the prediction correlation. A general and concise functional relationship for predicting breakthrough time was established based on simulation results and theoretical analysis. The breakthrough time of one conceptual model predicted by the correlation is very close to the result by Eclipse with less than 2% error. The practical breakthrough time of one well in Helder oilfield is 10 d, and the predicted results by the method is 11.2 d, which is more accurate than the analytical result. Case study indicates that the method could predict breakthrough time of horizontal well under different reservoir conditions accurately. For its university and ease of use, the method is suitable for quick prediction of breakthrough time.

Self-sealing of fractures in indurated claystones measured by water and gas flow

Self-sealing of fractures in the indurated Callovo-Oxfordian(COX)and Opalinus(OPA)claystones,which are considered as host rocks for disposal of radioactive waste,was investigated on artificially fractured samples.The samples were extracted from four lithological facies relatively rich in clay mineral,carbonate and quartz,respectively.The self-sealing of fractures was measured by fracture closure,water permeability variation,gas penetration,and recovery of gas-induced pathways.Most of the fractured samples exhibited a dramatic reduction inwater permeability to low levels that is close to that of intact rock,depending on their mineralogical composition,fracture intensity,confining stress,and load duration.The self-sealing capacity of the clay-rich samples is higher than that of the carbonate-rich and sandy ones.Significant effects of sample size and fracture intensity were identified.The sealed fractures become gas-tight for certain in-jection pressures.However,the measured gas breakthrough pressures are still lower than the confining stresses.The gas-induced pathways can recover when contacting water.These important findings imply that fractures in such indurated claystones can effectively recover to hinder water transport but allow gas release under relatively low pressures without compromising the rock integrity.

基于BP神经网络的低渗透底水油藏油井见水模式预测模型

注水开发使得低渗透底水油藏油井见水模式更加复杂,需要进一步明确及预测油井见水模式来针对性地指导水淹治理措施。神经网络模型具备处理多元回归问题和计算速度快等优势,可被用于分析地质工程多因素参数与油井见水模式的内在关系,构建见水模式预测模型。在油井见水模式划分的基础上,通过灰色关联理论和神经网络算法对BCL低渗透底水油藏油井见水模式的主控因素和预测模型进行了研究。发现水层厚度、隔夹层数、隔夹层长度和避水高度是该类油藏注水开发下影响油井见水模式的主控因素。基于主控因素结合神经网络算法建立了油井见水模式预测模型。通过对18组测试数据进行验证,平均预测误差1.4%,获得了较好的预测精度。通过易于获取的主控因素快速预测注水开发低渗透底水油藏油井的见水模式,为该类油藏的高含水针对性治理提供基础依据。

滇西南宿根甘蔗地土壤大孔隙特征

【目的】准确掌握宿根甘蔗土壤孔隙的变化特征,为甘蔗种植中的土壤管理、土壤水文预测预报等提供依据。【方法】采用空间代替时间法结合土壤水分穿透曲线法测定了不同坡度、不同宿根年限、不同土层的甘蔗地土壤大孔隙。【结果】宿根甘蔗地40 cm深土壤大孔隙半径分布在0.3~3.6 mm,随着孔径的增大,土层深度的增加,大孔隙数量显著减少;随着坡度和年限的增加,小于0.6 mm的大孔隙数量减少得更显著;土壤大孔隙平均半径最大为种植后第4年,且年限间差异主要出现在坡地上;坡地大孔隙面积比和平均体积呈现出随着宿根年限增加其值减小的趋势。【结论】甘蔗地宿根管理下,深层及小孔径大孔隙数量减少是主要趋势,应加强深施肥或原位松土管理。

地热水回灌耦合CO_(2)地质封存系统安全性分析

在圈闭良好的水热型地热储层,开展CO_(2)随回灌水同时注入储层的研究,既具有经济效益又具有碳封存的环境效益。建立了3D储层模型,对不同井距、地层倾角、筛管位置和采灌速率下CO_(2)突破时间以及富含CO_(2)的盐水在储层中的运移情况进行了研究。结果表明:(1)在采灌速率为20 kg/s,20 a运行时间内井距为1200 m时CO_(2)未突破;(2)在倾斜地层中,当回灌井位于开采井下游时,随地层倾角增加,CO_(2)突破时间延长,沿地层下倾方向碳酸水运移距离增大;(3)综合考虑筛管位置对突破时间和突破后开采井中CO_(2)质量分数的影响,回灌井筛管位于储层上部30 m、开采井筛管位于储层下部30 m时,有利于CO_(2)地质封存的安全性和有效性;(4)采灌速率对CO_(2)突破时间影响较大,当采灌速率为12 kg/s时,CO_(2)未突破;当采灌速率增加到28 kg/s时,突破时间缩短到11.8 a。因此,在实际工程应用中可以通过对操作参数和地层固有特性的研究延缓CO_(2)突破,提高CO_(2)地质封存安全性。

掺砂量对中度盐碱土壤水力特性及溶质运移过程的影响

[目的]为探究不同掺砂量对中度盐碱土壤水力特性和溶质运移过程的影响。[方法]采用室内土柱试验,设置4种掺砂比例CK(掺砂0)、B1(掺砂10%)、B2(掺砂15%)、B3(掺砂20%),研究中度盐碱土壤在不同掺砂量条件下的土壤水力特性和溶质运移过程变化规律并进行模型模拟。[结果](1)掺砂量在0~20%内,中度盐碱土掺砂明显影响土壤水分特征曲线变化,掺砂比例越大,曲线越靠近Y轴。在任一吸力条件下土壤含水率表现为CK>B1>B2>B3。且掺砂比例越大,土壤小孔隙数量越多,微小孔隙减少,土壤持水性能减弱。土壤的饱和导水率随掺砂量的增加而增大。(2)随掺砂量的增加,溶质穿透曲线明显左移,初始穿透时间、完全穿透时间及穿透总历时均减少,B1、B2、B3处理总穿透历时分别比CK减少34.48%,47.22%,69.71%。(3)CED方程和两区模型均能较好地模拟掺砂条件下土壤中溶质运移状况,但相较于CDE方程,两区模型的拟合精度更高。对两区模型拟合参数进行分析发现,随掺砂量的增加,土壤孔隙流速、可动区含水比率和质量交换系数逐渐增大,而水动力弥散系数和弥散度呈减小趋势。[结论]盐碱土掺砂能够有效改善土壤水力特性,促进溶质在土壤中运移,有助于缓解盐碱对作物生长的不利影响。研究结果可为盐碱土改良与治理工作提供参考,为未来的研究和实践提供理论支持和实践指导。

基于水体重力影响的底水气藏见水时间预测

底水气藏产水情况复杂,气井见水时间对底水气藏开发具有重大意义,以往对底水气藏见水时间的预测均未考虑水体重力的影响,导致对见水时间的预测不够准确。为进一步提高底水气藏见水时间预测的精度,基于渗流力学理论及流体在多孔介质中的流动规律,建立了考虑水体重力影响的底水气藏见水时间预测公式,运用单因素分析法研究了水体流度、水体密度、储层孔隙度、井底距底水距离及生产压差对见水时间的影响。研究表明:底水气藏见水时间与储层孔隙度、井底距底水距离呈正相关关系,与水体流度、水体密度及生产压差呈负相关关系。由于该方法引入水体密度来分析水体重力对气藏见水时间的影响,与忽略了水体重力影响的气藏见水时间预测方法相比,预测时间更符合气藏实际情况,对现场生产管理具有重要的指导意义。

广西水网先导区建设重点突破方向的思考

分析了广西水网发展现状及存在的问题,结合广西水网先导区建设目标、任务,提出了先导区建设重点突破方向,从水网关键工程建设、大石山区集中供水保障、新建大型灌区、水网水运融合发展等方面提出了建议。

海上边水稠油油藏见水时间预测新方法:以海上LD油田为例

边水油藏见水时间的准确预测有助于油田精准施策,实现控水稳油、提高采收率。以海上LD油田为研究对象,利用数值模拟技术研究了平均渗透率、级差、距边水距离、水体倍数、采油速度、原油粘度等因素对见水时间的影响规律,并利用相对极差法确定主控因素。在此基础上,利用正交设计法设计模拟方案,根据模拟结果回归边水油藏见水时间预测的经验公式。研究表明:距边水距离、采油速度、级差、原油粘度是影响LD油田见水时间的主控因素;经验公式的预测结果拟合精度达到0.93,现场计算结果与油田实际情况一致;研究成果指导高含水井确定出水层位,卡水作业后,X19井日增油10 m^(3)/d,对于提高边水油藏的开发效果具有一定指导意义。

Effect of Polyacrylamide Application on Water and Nutrient Movements in Soils

An understanding of nutrient movement in soil is important for developing management strategies to minimize nutrient leaching and surface movement, thus improving nutrient uptake by plants, maintaining a sustainable soil system, and even protecting groundwater quality. Polyacrylamide (PAM) is known as one of soil conditioner that functions to stabilize soil structure, increase infiltration, and reduce surface runoff. This study assesses the effects of PAM on the vertical movement of soil-water and major/minor nutrients (NO3-N, NH3-N, T-N, PO4-P, T-P, K, Ca, Mg, and Fe) in soils. Saturated hydraulic conductivity (Ksat) increases with increasing PAM concen- trations up to 10 mg·L-1 for sand and 20 mg·L-1 for a mixture of sand and clay. Decreases in the loss of soluble nutrients, particularly NH3-N, PO4-P and T-P, are observed as PAM concentrations increase. In contrast, PAM concentration has no effect on nitrate and minor nutrient levels. These results indicate that the application of PAM may be a viable method for protecting water bodies from excessive nutrients and improving nutrient availability for plants.

Adsorption Breakthrough of Benzene in the Fixed Bed of Modified Activated Carbon under Different Humidity Conditions

The breakthrough curves of benzene and water on modified activated carbons（ACs） were investigated.Temperature-programmed desorption（TPD） experiments were conducted to measure the TPD curves of benzene and water on modified and unmodified ACs and to estimate the activation energy for the desorption of benzene on the modified ACs.Starting with unmodified ACs,two modified ACs were prepared by using two different types of silane,designated by KH560 and 1706.The results showed that the activation energy for the desorption of benzene on KH560/AC and 1706/AC was higher than that on unmodified AC.In addition,the activation energy for the desorption of water on KH560/AC and 1706/AC was lower than that on unmodified AC.The breakthrough curves of benzene obtained from the experimental observations under different humidity conditions were compared with the results of the TPD experiments.The results show that the modified ACs are less affected by water,whereas the unmodified ACs are more affected by water,indicating that surface modification by organosilane compounds can improve the adsorption of benzene on the activated carbo,which weakens the adsorption of water.

多层系边底水气藏生产动态特征及见水时间预测方法

针对多层系气田不同层之间压力系统、水体能量、储层物性不同而导致的气藏生产动态规律差异明显的现象,以Z气田为例,分析了气井生产过程中凝析油含量变化规律,明确了影响凝析油含量变化的主控因素。研制了气井出水类型判别图版,通过计算井底与井口2种条件下天然气饱和水量的差值,能够判别气井出水类型。采用现代产量递减分析方法确定地层压力变化规律,基于气藏物质平衡方法,计算不同时刻气井的水侵量和水侵替换系数,明确了气井3种见水模式。建立了考虑储层倾角的边水气藏见水时间解析预测方法,研制了不同储层倾角、日产气量情况下的见水时间预测图版,为Z气田未投产气藏以及同类型气藏的高效开发提供了技术支撑。

Importance of Water Chemistry in Oil and Gas Operations—Properties and Composition

In the oil and gas industry, water is essential element since it exists in most of the stages, starting from drilling operations, then production processes including injecting in the reservoir to maintain the pressure, and finally disposing the produced water from the reservoir. Therefore, it is very important to understand the water in the petroleum industry with its different types and study its effects on the reservoirs as well as the downhole and surface equipment. Most of the studies and literature reviews focused on the oil and gas properties. In fact, understanding the properties of the water is as important as the oil and gas properties. Water is always present in the oil and gas fields during production, injection or disposal. Therefore, it has a direct impact on the productivity and overall efficiency of the field and the entire development project. This paper is going to illustrate and focus on several objectives. First, it elaborates the importance of the water in the oil and gas fields. Then, it includes a comprehensive overview of different types of water in the petroleum industry including a summary about of their properties. The main two types that the paper focuses on are the produced water and the injected water. It clarifies the effects of both of them on the reservoir, well completions and facilities. After that, the paper touches bases on the common problems and issues caused by water along with a brief summary of steps needed by the operators to follow in order to solve them. In addition to that, the common monitoring procedures and tests that are usually followed to observe the quality of the water are going to be presented. Finally, couples of solutions used by operators are reviewed to solve the problem of excessive water production after the water breakthrough in the field.

Batch and fixed-bed column studies of selenite removal from contaminated water by orange peel-based sorbent

Orange peel is a biomass derived from citrus processing with desirable properties for metal sorption.In recent years,orange peel has been used to remove various heavy metals and toxic oxyanions.Selenium(Se)is an essential trace element for mammals.However,when the concentration of selenium exceeds an umbral limit,it becomes toxic.In this study,orange peel was used to treat Se(IV)-contaminated water.A high sorption capacity of 32.5 mg/g was obtained at a temperature of 20℃and a pH of 2.0.Hydroxyl groups bound Se(IV)to the surface of the orange peel.The sorption process was spontaneous and endothermic.A chemical sorption mechanism was involved in the removal of Se(IV).The Thomas and modified dose-response models were used to simulate the experimental breakthrough curves.The bed depth service time model was used to calculate the critical bed depth(Z0),and the calculated Z0 value was 1.6 cm.This study reveals that orange peel is a useful sorbent for Se(IV),and can be used for the purification of Se(IV)-contaminated water.©2020 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

缝洞型碳酸盐岩底水气藏水侵规律预测新方法

国内缝洞型碳酸盐岩底水气藏资源潜力巨大,但该类气藏储层的孔隙、溶洞、裂缝普遍发育,非均质性强且气水关系复杂,开采过程中底水容易沿高渗透率缝洞区窜流,导致气井产出地层水,大幅降低气井产能及气藏采收率。因此,正确认识气藏水侵规律是该类气藏高效开发的关键。为此,以四川盆地中部地区缝洞型碳酸盐岩底水气藏为例,针对气藏储层非均质性强的特点,将其抽象为不同渗透率分布的复合储层模型,进而基于稳态渗流理论,建立了一种计算缝洞型底水气藏的气井临界产量、水侵速度和底水突破时间的新方法,应用于典型气井,并利用数值模拟技术验证了该预测方法的可靠性。研究结果表明:(1)气井临界产量随射孔段储层厚度的增加呈先增大后减小的变化规律,且存在一个最优值;(2)底水优先突破位置受生产压差和高渗带分布位置双重作用影响;(3)为延缓气井见水时间、提高气藏采收率,气井配产应不高于临界产量。该研究成果可为缝洞型碳酸盐岩底水气藏水侵动态分析以及整体治水提供技术支撑。

滇西南不同土地利用方式坡地土壤大孔隙特征及与饱和导水率的关系

【目的】研究滇西南不同土地利用方式坡地土壤大孔隙特征与饱和导水率的变化,为控制滇西南地区坡地水土流失提供参考。【方法】以滇西南6种典型土地利用方式(荒草地、茶地、烤烟地、玉米地、甘蔗地、澳洲坚果地)坡地为研究对象,测定6种坡地不同坡位(坡上、坡下)和土层(0~15,15~30 cm)土壤的基本理化性质、水分穿透曲线、大孔隙特征及饱和导水率,分析不同土地利用方式坡地土壤大孔隙特征与饱和导水率的关系。【结果】(1)滇西南不同土地利用方式坡地土壤基本理化性质存在差异,坡位和土层深度对土壤的基本理化性质有明显影响。(2)滇西南不同土地利用方式坡地的土壤水分出流速率先增加,都在90 s之后基本趋于稳定。6种土地利用方式下0~30 cm土层土壤平均出流速率表现为玉米地>荒草地>澳洲坚果地>茶地>甘蔗地>烤烟地。(3)不同土地利用方式坡地土壤大孔隙半径、面积比与平均体积存在明显差异。荒草地、茶地、玉米地、澳洲坚果地土壤大孔隙平均半径随土层深度的增加而减小,而甘蔗地、烤烟地土壤大孔隙平均半径变化则相反。不同土地利用方式坡地土壤大孔隙面积比与平均体积由大到小均表现为玉米地>荒草地>澳洲坚果地>茶地>甘蔗地>烤烟地。(4)不同土地利用方式坡地土壤饱和导水率差异显著,其中玉米地和荒草地饱和导水率明显高于其他坡地。(5)相关性分析表明,不同土地利用方式坡地土壤大孔隙密度、平均体积与饱和导水率呈线性正相关关系,平均半径与饱和导水率之间呈指数函数关系。土壤大孔隙平均体积与稳定出流速率之间呈线性正相关关系。【结论】不同土地利用方式坡地表层(0~15 cm)和上坡位土壤大孔隙半径大、联通性好,更有利于土壤的滞水减流。

CO_(2)封存中盖层突破压力计算与分析

盖层是CO_(2)封存中最重要的地质构造组成,其封闭能力的表征方法是目前研究的热点。针对盖层封闭能力评价的问题,在耦合平行毛管束与DLVO(带电表面通过液体介质的微观作用力)理论的基础上,考虑滑移效应和水膜效应,建立了盖层突破压力的理论计算方法,并与实验数据进行准确度验证。通过影响因素分析研究了突破压力随滑移长度、有效毛管半径的变化规律。结果表明:6块岩心样品的突破压力计算结果与实验数据相对误差介于0.317%~10.800%;滑移长度越小、有效毛管半径越大,突破压力越小。

Design of Pilot Plant Packed Column for the Dehydration of Water from Ethanol-Water Mixtures

This use of biomass-based adsorbent has been explored for the column study of the adsorptive dehydration of water in ethanol-water mixtures. The column study was carried out using enzyme modified corn starch and the breakthrough curve parameters were used to design the packed bed column. The effect of flow rate on the breakthrough curves revealed that adsorption efficiency decreased with increased inflow rate. The empty bed contact time (τ) of the pilot plant packed column was 35.35 min while the breakthrough time is 40.78 min. 66.7% was the fraction of capacity left unused for the pilot plant from the design.

M30油藏长8储层见水规律及治理对策研究

M30油藏在开发过程中,见水矛盾突出,以裂缝型见水为主。通过油水井双向调控,逐步形成周期注水+微球调驱技术、水平井找堵水技术、冲砂酸化补能技术,其中周期注水+微球调驱技术更适应于孔隙-裂缝渗流单元,水平井化学堵水单井日增油效果突出,冲砂酸化补能技术的分段补能效果优于笼统补能。