钻井优化系统在国内非常规油气资源开发中的实践

相对于北美,国内非常规油气资源勘探开发起步较晚。页岩气勘探开发始于"十二五"初,致密油、致密气、页岩油勘探开发则始于"十三五"初,但在"十三五"期间得到了快速发展,特别是川渝页岩气藏、准噶尔盆地玛湖砾岩油藏、吉木萨尔页岩油藏已进入规模开发阶段,成为中国石油"十三五"末及"十四五"期间天然气和原油上产的最重要领域。与常规油气资源相比,非常规油气资源储层条件差,需要大规模"水平井+体积压裂"才能实现有效开发。然而,由于受钻机装备条件和水平井钻井工具性能,特别是理念和方法的限制,国内非常规水平井普遍存在钻井效率低、建井周期长的问题:一般垂深为2000~3000m、水平段长1500~2000m的水平井钻井周期为60~90天。而北美钻一口水平井基本都能控制在15~25天:一般垂深为2000~3000m、水平段长2000~3000m。国内一部钻机一年只能钻2~3口水平井,而在北美一部钻机一年能完成15~20口水平井。随着国内非常规油气资源的规模开发,钻机紧缺的矛盾日益突出,钻井效率已经成为严重制约国内非常规油气资源快速规模上产的瓶颈问题。北美大幅度提高水平井钻井效率的原因有管理和技术两大因素,其中技术主要表现在以下5个方面:一是钻机配套能力的不断升级;二是井下工具可靠性和稳定性的提升;三是大平台工厂化作业;四是远程实时支持与决策系统;五是系统优化钻井理念和方法的应用。2018年海峡能源股份有限公司与美国K&M钻井工程咨询公司合作,引进国际先进的系统优化钻井理念和方法,率先在川渝地区长宁页岩气藏和新疆玛湖砾岩油田开展了水平井钻井提速先导性试验,大幅缩短了建井周期,验证了系统优化钻井方法在国内非常规油气资源开发中的可行性。为了达到进一步推广的目的,2019年在玛湖砾岩油田开展区块提速试验,同样取得了显著的提速效果,进一步证明了系统优化提速理念和方法具有科学性、广普性和可复制性,是经验钻井向科学钻井迈进的重要实践,展示出了非常广阔的推广应用前景。

Practice of drilling optimization system in the development of unconventional oil and gas resources in China

Compared with North America,the exploration and development of unconventional oil and gas resources in China started relatively late.Shale gas exploration and development began at the beginning of the“12th Five Year Plan”.The exploration and development of tight oil,tight gas and shale oil started at the beginning of the“13th Five Year Plan”,and developed rapidly during the“13th Five Year Plan”.In particular,the developments of shale gas in Sichuan and Chongqing,conglomerate oil fi eld in Mahu sag in the Junggar Basin and shale oil reservoir in Jimsar have entered the stage of large-scale development,becoming the most important fi eld of oil and gas production increase in the end of the“13th Five Year Plan”and the period of“14th Five Year Plan”of CNPC.Compared with conventional oil and gas resources,unconventional oil and gas resources have poor reservoir conditions,which requires large-scale“horizontal well+volume fracturing”to achieve effective development.However,due to the limitations of rig equipment and the performance of horizontal well drilling tools,especially the limitations of the concepts and methods,the issues of low drilling effi ciency and long well construction period are common in unconventional horizontal wells in China.Generally,the drilling period of horizontal well is 60-90 days with vertical depth of 2000-3000 m and horizontal section of 1500-2000 m.In North America,drilling period of a horizontal well can be basically controlled within 15-25 days with vertical depth of 2000-3000 m and horizontal section length of 2000-3000m.A drilling rig in China can only drill 2-3 horizontal wells a year,while in North America a drilling rig can complete 15-20 horizontal wells a year.With the large-scale development of unconventional oil and gas resources in China,the contradiction of drilling rig shortage is increasing.Drilling effi ciency has become a bottleneck problem that seriously restricts the rapid and large-scale production of unconventional oil and gas resources in China.There are 2 advantages for the great improvement of drilling effi ciency of horizontal wells in North America:management and technology.For technology,there are mainly 5 aspects:fi rst is the continuous upgrading of drilling rig supporting capacity;second is the improvement of the reliability and stability of downhole tools;third is the largeplatform factory operation;fourth is the remote real-time support and decision-making system;and fi fth is the application of the concepts and methods of systematic drilling optimization.In 2018,Strait Energy cooperated with K&M drilling engineering consulting company of the United States to introduce internationally-advanced concepts and methods of systematic drilling optimization.The pilot test of drilling speed increase of horizontal well was fi rst carried out in Changning Shale Gas Co.,Ltd.in Sichuan and Chongqing area,and conglomerate oil fi eld in Mahu sag in Xinjiang,which greatly shortened the well construction period and verifi ed the feasibility of systematic drilling optimization methods in the development of unconventional oil and gas resources in China.In order to further promote,in 2019 the test of speed increase in whole block was carried out in conglomerate oil fi eld in Mahu sag,which also achieved remarkable results.It further proves that the concepts and methods of systematic optimized drilling speed increase are scientific,universal and replicable,which is an important practice from experience drilling to scientifi c drilling,and shows a very promising popularization and application prospect.