【作者】 曲同慈；

【导师】 张金亮；

【作者基本信息】 中国海洋大学 ， 海洋地球物理学， 2010， 博士

【摘要】 辽河盆地经过近40年勘探开发,已探明稠油地质储量超过10亿吨,动用稠油储量约7.4亿吨,稠油产量已占辽河油田总产量的60%以上。虽然,由于蒸汽吞吐技术及开采工艺的进步,稠油油藏得到了全面开发,但进入高轮次吞吐后周期油气比已接近经济极限,直井单井控制储量低,井况变差,边底水侵入,稳产难度大,特超稠油油藏蒸汽吞吐波及范围小,采出程度低。为了有效改善稠油油藏开发效果,提出了利用水平井方式整体调整部署开发稠油油藏的研究项目,重点开展了3个方面的研究：(1)辽河盆地稠油油藏剩余油富集规律研究及水平井油藏工程设计应用实验。利用开发油藏动态测试技术,地球物理测井精细解释技术,动边界、无网格油藏工程计算技术,油藏数值模拟技术,对目标区块开展精细构造描述、储层描述、流体性质分析、已钻井生产状况分析等技术分析,找出稠油油藏高轮次蒸汽吞吐后残余油富集区,建立高轮次蒸气吞吐直井间剩余油饱和度模型,对边、底水和薄层等典型稠油油藏应用水平井技术开展老油田整体部署水平井调整开发方案研究试验。(2)辽河盆地西部凹陷稠油油藏水平井钻井技术研究。针对稠油油藏地层易垮塌、井漏等不稳定特点,从储层分布预测、导眼井优化设计、井眼轨迹优化设计、井身结构优化设计、完井方式优选等方面,对水平井单井地质工程设计精细研究,并现场实时动态跟踪,实现安全钻井。(3)特超稠油油藏水平井水平段注汽工艺技术研究。针对井深、油稠、水平段长等特点,开展了注汽参数优选、注汽方式、隔热方式等研究,提高了注汽隔热效果,实现稠油油藏均匀受气,为提高采收率奠定基础。通过上述研究,获得了如下4项认识：(1)特超稠油高轮次吞吐井井筒周围压力较低,而其它区域仍较高；温度在井点附近30-50m有不等提高,其它区域仍为原始温度；含油饱和度在井间基本为原始饱和度的65%；原油粘度在井筒50m附近下降大,以外则基本保持原始水平。(2)构造高部位受底水锥进影响小,井间剩余油较富集；受边底水共同作用,低部位水淹较重,水淹面积连片分布。水平井可有效减缓边底水推进速度,提高油藏动用程度。(3)现场地质导向是水平井成功实施的保证。对地质条件复杂,断层发育,构造起伏大,储层横向变化大的水平井钻井,必须进行地质导向。根据室内建立的水平井在造斜过程中不同井斜角度变化与岩屑迟到时间对应关系解释图版,不同钻具组合方式(螺杆钻进或旋转钻进)对应不同地层岩性、钻时、钻压变化解释图版进行现场实时跟踪,可提高地质跟踪精确度,保证了油层钻遇率。(4)经济评价分析表明,水平井平均单井投资为直井的2.0～2.5倍；平均单井产量是直井的2-4倍；平均单井年操作成本为直井的0.5～0.66倍；在评价期内,平均水平井单井方案财务净现值是直井方案的23.8倍。水平井开发稠油油藏经济可行,且可获得较好经济效益。通过本项目攻关研究,取得了4个方面的技术成果：(1)创建了用于提高特超稠油油藏水平井轨迹跟踪精度的现场钻井分析控制技术。根据室内建立的水平井在造斜过程中不同井斜角度变化与岩屑迟到时间对应关系的解释图版,建立了不同钻具组合方式(螺杆钻进或旋转钻进)对应不同地层岩性、钻时、钻压变化的关系图版,在水平井钻进时进行现场实时跟踪,大大提高了水平井井身轨迹跟踪精确度。(2)针对特超稠油油藏松散地层的特点,优化了安全快速钻井的水平井钻具组合,提高了水平段携岩能力,开发了水平井井眼净化的钻井泥浆配方体系。应用水平井专用工具,确保套管与井壁间的线接触力均匀微渐增分布,无峰值突变,最大应力小于极限应力一半的安全钻井技术方案；优化设计轨迹,造斜率形成由上大下小的渐增式轨迹；采用抗高温、阻漏失的适应高温亏空油藏的钻井液体系来保证正常钻进,解决了稳定井眼和油层保护的矛盾,有效的保证钻井安全,提高了钻井速度。(3)研制了“J”型水平井钻井技术,解决了顶水稠油油藏水平井水平段固井的难题。对于顶水稠油油藏水平井造斜段为松散砂砾岩、固井质量差,研究出利用水平轨迹反穿过油藏下部稳定泥岩再进入油层的钻井方式,即“J”型水平井,确保大斜度段固井质量达到提高固井质量的目的。(4)建立了特超稠油油藏直井高轮次蒸汽吞吐后,老油田整体部署水平井调整开发方案的水平井油藏工程设计技术。通过油藏数值模拟,建立实验区地质模型和网格系统；通过基础数据分析和历史拟合,观察压力、温度的波及范围,确定剩余油含油饱和度的变化规律；按照剩余油分布规律,合理选择水平井平面和纵向位置、最佳水平段长度、最优注蒸汽参数等。更多还原

【Abstract】 After almost 40 years of exploration and development, Liaohe Basin has discovered proved heavy oil in place of over 1 billion tons, produced heavy oil reserves of about 0.74 billion tons, and the heavy oil production of Liaohe Oilfield has accounted for over 60% of its total production. Although heavy oil reservoirs have been put into full-scale development owing to the advances in cyclic steam stimulation technology and production practice, the cyclic oil-steam ratio has been near the economic limit in later cycles of steam stimulation, the reserves controlled by single vertical wells are low, the well conditions deteriorate, edge and bottom water encroaches, stable production is difficult to achieve, steam conformance area for ultra heavy oil is limited, and the recovery percent of reserves is low.In order to improve the development efficiency of heavy oil reservoirs, a substantial amount of investigations has been conducted for horizontal well drilling technology and application at home and abroad, the research project of adjusting, planning and developing heavy oil reservoirs by using horizontal wells has been proposed, and the study mainly involves 3 aspects:(1) The study of residual oil distribution and the applied experiment of reservoir engineering design with horizontal wells for heavy oil reservoirs in Liaohe Basin. The target zones are technically analyzed in respects of fine structure description, reservoir description, sedimentary facies description, fluid property analysis, and well production conditions by using testing techniques of reservoir performance, fine interpretation of geophysical logging, reservoir engineering calculation with produced boundary and without grid, and numerical simulation. The areas rich in residual oil after many cycles of steam stimulation have been determined, a model of residual oil saturation between vertical wells has been built, and research trials of adjusting development program have been conducted for typical old heavy oil reservoirs with edge and bottom water and thin layers by using horizontal well technology. (2) Study on horizontal well drilling technology for heavy oil reservoirs in the Western Depression of Liaohe Basin. In order to implement scale application of horizontal well technology to heavy oil reservoirs, meticulous study has been conducted for geological engineering design of single horizontal well in respects of reservoir distribution prediction, pilot hole optimization, well path optimization, hole structure optimization and completion optimization in accordance with the uncertainties of formation caving and lost circulation in heavy oil reservoirs. Dynamic tracking has been carried out on site to realized safe drilling. (3) Study on steam injection technique for horizontal section of horizontal wells in ultra heavy oil reservoirs. In accordance with the characteristics of deep well, heavy oil and long horizontal section, the parameters of steam injection are optimized, the methods of steam injection and heat insulation are studied, thus improved steam injection and heat insulation effects, realized even injection in heavy oil reservoirs, and laid basis for improving recovery factor.The following 4 cognitions have been acquired through the studies above:(1) Except the low pressure around wells experienced many cycles of steam stimulation, the other areas in ultra heavy oil reservoirs still maintain at initial pressure; the temperature increases differently at 30～50m from the well, and most of the rest part still keeps at original reservoir temperature; oil saturation between wells is basically about 65% of the initial saturation; oil viscosity reduces a lot at about 50m to around wellbore, and keeps almost at the original level beyond; (2) the structural high is less affected by bottom water coning and has rich remaining oil; the structure low is severely watered out as affected by both edge and bottom water. Horizontal well can effectively slow down the speed of edge and bottom water advancing, and improve the producing degree of reservoirs. (3) Geosteering is a guarantee for successful drilling of horizontal wells. For drilling in reservoirs with complex geological conditions, developed faults, big structural relief and drastic lateral change of reservoirs, geosteering must be applied. Geosteering performs real time follow-up according to the interpretation chart of the corresponding relationship between deviation angles and cutting lag time during build-up process, as well as the interpretation chart of the correspondence between different drilling assembly (screw drilling or rotary drilling) and lithology, rig time and drill pressure in different formations. It improves the accuracy of geologic tracking and ensures reservoir encountering rate. (4) The result of economic evaluation analysis indicates that, the average single horizontal well investment is 2.0-2.5 times of that of the vertical well; the average single well production is 2-4 times of that of the vertical; the average annual operation cost of single horizontal well is 0.5-0.66 time of that of the vertical; within the evaluation period, the average net present value of single horizontal wells is 23.8 times of that of the vertical. Horizontal well is an economic way for developing heavy oil reservoirs and can achieve better economic benefits.This research study has obtained technical achievements in 4 aspects:(1) Drilling analysis and control technology for improving well path accuracy in ultra heavy oil reservoirs. The relationship chart of different drilling assembly (screw drilling or rotary drilling) corresponding to lithology, rig time and drill pressure in different formations has been established according to lab established interpretation chart of the corresponding relationship between deviation angles and cutting lag time during build-up process. Real time tracking has been conducted during horizontal well drilling, and the accuracy of well path tracking has been greatly improved. (2) Horizontal well drilling assembly has been optimized in accordance with the features of unconsolidated ultra heavy oil reservoirs for safe and fast drilling, the capacity of cutting-carrying in horizontal section has been improved, and the drilling fluid system of hole cleaning has been developed for horizontal well. Special tools for horizontal well has been use to ensure that the lineal contact force between casing and sidewall distributes in a uniformly, slightly and gradually increasing pattern without abrupt change of peak value, and the maximum stress is less than half of the limit stress. Well path design is optimized to form gradual building up; the drilling fluid system of high temperature resistance and lost circulation prevention suitable to high temperature voided reservoirs has been used to solve the problem between hole stability and reservoir protection, thus ensured safe drilling and improved drilling speed. (3) J-shape horizontal well drilling technology has been developed for the problem of horizontal section cementation in heavy oil reservoirs with top water. For heavy oil reservoirs with top water, where the build-up section is unconsolidated glutenite and cementing quality is poor, a drilling method of reverse drilling from the stable mudstone below to enter the reservoir has been developed, i.e., J-shape horizontal well, thus improved cementing quality in highly deviated section. (4) The technology of ultra heavy oil reservoir engineering with horizontal wells has been developed for overall adjustment of old oilfield development after many cycles of steam stimulation. Geological model and grid system are constructed for pilot area through numerical simulation; the conformances of pressure and temperature are observed through basic data analysis and history match; the distribution of residual oil saturation is determined; and the lateral and vertical location of horizontal well, the optimum length of horizontal section, the optimum steam injection parameters are selected according to residual oil distribution.更多还原