W12油田群井壁稳定及井身结构优化研究
发布时间：2019-04-09 08:31
【摘要】：井壁稳定问题是钻井工程中经常遇到的一个十分复杂的难题,W12油田群位于南海西部北部湾盆地,在近期钻井作业中该地区常常遇到井壁失稳而影响钻井速度的情况,造成作业时效低,成本高,严重影响钻完井勘探开发的进度,并影响最后的综合经济效益。W12油田群是即将开发的新油田,计划新建多个平台进行开发,开发几十口井。纵观前期邻井的钻井作业概况,并结合本期钻井规划,归纳该油田群作业难点如下：断层、裂缝发育,岩石易水化,易发生垮塌；井深较大：平均井深三千多米；超过四千米井多口；最大井深达到将近五千米,导致裸眼段很长,增加了井壁岩石的浸泡时间；多口井压力系数超过平均水平,所需泥浆比重高,易压漏地层；可钻性差,导致机械钻速降低,增加了裸眼的暴露时间；轨迹复杂,含大斜度长稳斜段,易发生其它复杂情况。这些复杂情况也对井深结构的优化选择造成了很大困难。本文针对W12油田群存在的问题,运用测井、地质以及钻完井资料,通过大量的调研工作,结合该研究区域钻井工程难点和地层特征,开展W12油田群地区井壁稳定及井身结构优化研究。通过建立地层孔隙压力计算模型,利用地质、录井、钻井、测井、测试资料,结合油田的地质情况,确定地层孔隙压力纵向分布规律,进一步研究地层孔隙压力横向分布规律。通过实验对地层坍塌周期进行了分析预测,从而研究井壁坍塌周期与钻井液体系及钻井液密度间的关系。最后根据W12油田群的地层孔隙压力、破裂压力和坍塌压力的分布规律以地层不压漏、不坍塌及经济钻达目的层为原则,确定出该井区单井合理的井身结构。研究的过程中主要解决了以下问题：(1)油田群断层、裂缝发育,岩石易水化,总体上讲,前期井壁失稳比较严重,需要弄清楚各层位发生井壁失稳的原因,检测那些层位易发生漏失,并精确计算地层三压力,得到相应的压力剖面推荐安全泥浆密度窗口,以便作业时选择合适的泥浆比重与性能。(2)通过室内力学实验得到岩石力学参数,并针对本地区岩石进行地应力测试及地应力剖面的确定,对该地区井壁稳定进行评价分析。(3)油田群本期钻井井深较大,部分井钻遇可钻性差地层,且轨迹复杂,裸眼暴露时间长,因此需要估算垮塌周期,得到裸眼暴露时间的极限数据,为井身结构设计提供基础数据。(4)结合地层三压力计算结果和垮塌周期分析结果,对ODP推荐的井身结构进行优化,以减少复杂情况的发生,降低作业成本。
[Abstract]:Wellbore stability is a very complicated problem frequently encountered in drilling engineering. W12 oilfield group is located in the Beibu Gulf basin in the west of South China Sea. In recent drilling operations, the borehole wall instability often affects the drilling speed in this area, and the W12 oilfield group is located in the Beibu Gulf basin in the western part of the South China Sea. The W12 oilfield group is a new oilfield to be developed, which plans to build several new platforms to develop and develop dozens of wells. The W12 oilfield group is a new oil field to be developed, which plans to build several new platforms to develop and develop dozens of wells due to the low operating time limit, high cost and serious influence on the progress of drilling and completion exploration. Taking a comprehensive view of the drilling operations of the adjacent wells in the early stage and combining with the drilling planning in this period, the difficulties in the operation of the oilfield group are summarized as follows: faults, fracture development, easy hydration and collapse of rocks, large depth of wells, average depth of more than 3,000 meters; The maximum depth of the well is nearly 5,000 meters, which leads to a long open hole section, which increases the immersion time of the borehole rock, and the pressure coefficient of the multiple wells exceeds the average level, the specific gravity of the mud required is high, and the formation easily lost pressure is easy to be lost. The poor drillability leads to the decrease of the mechanical drilling rate and increases the exposure time of the open hole, and the trajectory is complex and contains a long and stable slope section with large inclination, so it is easy to occur other complicated situations. These complex conditions also make it difficult to optimize the well depth structure. In view of the problems existing in W12 oilfield group, this paper uses logging, geology and drilling and completion data, through a lot of investigation work, combined with the difficulties and formation characteristics of drilling engineering in this study area. The study on wellbore stability and wellbore structure optimization in W12 oilfield group area was carried out. By establishing the calculation model of formation pore pressure, using geological, logging, drilling and testing data, combined with the geological conditions of oil field, the vertical distribution of formation pore pressure is determined, and the transverse distribution of formation pore pressure is further studied. The collapse period of formation is analyzed and predicted by experiments, so as to study the relationship between wellbore collapse period and drilling fluid system and drilling fluid density. Finally, according to the distribution law of formation pore pressure, fracture pressure and collapse pressure in W12 oilfield group, the reasonable wellbore structure of single well in this well area is determined according to the principle of formation non-pressure leakage, non-collapse and economic drilling to reach the target layer. In the course of the research, the following problems have been solved: (1) the faults of the oilfield group, the development of fractures, the easy hydration of rocks, and, in general, the serious instability of the wellbore in the early stage, so it is necessary to find out the cause of the instability of the wellbore in each stratum. The leakage of those layers is easy to occur, and the three pressure of formation is calculated accurately, and the safe mud density window is recommended by the corresponding pressure profile. In order to select suitable specific gravity and properties of mud during operation. (2) the rock mechanics parameters are obtained through laboratory mechanics experiment, and the in-situ stress test and the determination of in-situ stress profile are carried out according to the rock in this area. The wellbore stability in this area is evaluated and analyzed. (3) the depth of drilling wells in this period of oilfield group is large, some wells have poor drillability formation, and the trajectory is complex and the exposure time of open hole is long, so it is necessary to estimate the collapse period. The limit data of open hole exposure time are obtained to provide the basic data for wellbore structure design. (4) combined with the results of formation three pressure calculation and collapse period analysis, the wellbore structure recommended by ODP is optimized to reduce the occurrence of complex situations. Reduce activity-based costs.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE26
本文编号：2455002
[Abstract]:Wellbore stability is a very complicated problem frequently encountered in drilling engineering. W12 oilfield group is located in the Beibu Gulf basin in the west of South China Sea. In recent drilling operations, the borehole wall instability often affects the drilling speed in this area, and the W12 oilfield group is located in the Beibu Gulf basin in the western part of the South China Sea. The W12 oilfield group is a new oilfield to be developed, which plans to build several new platforms to develop and develop dozens of wells. The W12 oilfield group is a new oil field to be developed, which plans to build several new platforms to develop and develop dozens of wells due to the low operating time limit, high cost and serious influence on the progress of drilling and completion exploration. Taking a comprehensive view of the drilling operations of the adjacent wells in the early stage and combining with the drilling planning in this period, the difficulties in the operation of the oilfield group are summarized as follows: faults, fracture development, easy hydration and collapse of rocks, large depth of wells, average depth of more than 3,000 meters; The maximum depth of the well is nearly 5,000 meters, which leads to a long open hole section, which increases the immersion time of the borehole rock, and the pressure coefficient of the multiple wells exceeds the average level, the specific gravity of the mud required is high, and the formation easily lost pressure is easy to be lost. The poor drillability leads to the decrease of the mechanical drilling rate and increases the exposure time of the open hole, and the trajectory is complex and contains a long and stable slope section with large inclination, so it is easy to occur other complicated situations. These complex conditions also make it difficult to optimize the well depth structure. In view of the problems existing in W12 oilfield group, this paper uses logging, geology and drilling and completion data, through a lot of investigation work, combined with the difficulties and formation characteristics of drilling engineering in this study area. The study on wellbore stability and wellbore structure optimization in W12 oilfield group area was carried out. By establishing the calculation model of formation pore pressure, using geological, logging, drilling and testing data, combined with the geological conditions of oil field, the vertical distribution of formation pore pressure is determined, and the transverse distribution of formation pore pressure is further studied. The collapse period of formation is analyzed and predicted by experiments, so as to study the relationship between wellbore collapse period and drilling fluid system and drilling fluid density. Finally, according to the distribution law of formation pore pressure, fracture pressure and collapse pressure in W12 oilfield group, the reasonable wellbore structure of single well in this well area is determined according to the principle of formation non-pressure leakage, non-collapse and economic drilling to reach the target layer. In the course of the research, the following problems have been solved: (1) the faults of the oilfield group, the development of fractures, the easy hydration of rocks, and, in general, the serious instability of the wellbore in the early stage, so it is necessary to find out the cause of the instability of the wellbore in each stratum. The leakage of those layers is easy to occur, and the three pressure of formation is calculated accurately, and the safe mud density window is recommended by the corresponding pressure profile. In order to select suitable specific gravity and properties of mud during operation. (2) the rock mechanics parameters are obtained through laboratory mechanics experiment, and the in-situ stress test and the determination of in-situ stress profile are carried out according to the rock in this area. The wellbore stability in this area is evaluated and analyzed. (3) the depth of drilling wells in this period of oilfield group is large, some wells have poor drillability formation, and the trajectory is complex and the exposure time of open hole is long, so it is necessary to estimate the collapse period. The limit data of open hole exposure time are obtained to provide the basic data for wellbore structure design. (4) combined with the results of formation three pressure calculation and collapse period analysis, the wellbore structure recommended by ODP is optimized to reduce the occurrence of complex situations. Reduce activity-based costs.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE26
【参考文献】
相关期刊论文 前2条
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，本文编号：2455002
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