海上气田开发评价中合理井距确定方法

Methods for determining reasonable well spacing in evaluation on offshore gasfield development

海上气田评价阶段,受限于评价井数量和地质资料,常规气田开发井距确定方法应用受限。通过分析常用的开发井距确定方法,选取普适性较好的单井合理控制储量法、合理单井配产法和合理采气速度法等3种方法进行分析,明确了该类方法开发井距确定中的关键参数,即气井稳定产量、合理采气速度、稳产年限及稳产期末采出程度,基于类比数据进行图版回归,明确了各关键参数的取值方法。此外,通过统计回归和概率分析方法,形成了不同物性条件下、不同气藏类型的经验图版。研究结果表明:①统计回归表格及图版可快速确定影响气田开发的相关关键参数,即合理采气速度、稳产年限及稳产期末采出程度;②基于已开发气田形成的气田井控面积法与单位厚度井控储量法,可用于气田开发井距的直接读取和快速确定;③相关研究成果在西非深水气田A中得到成功应用,确定该深水低渗气田合理井距为1000~1200 m。研究成果可为气田开发评价中合理井距的确定提供经验和借鉴。

In the evaluation on offshore gasfields,conventional approaches to determine well spacing are limited by the number of appraisal wells and the availability of geological data.Three universal ones among them were selected as research objectives,including reasonable well-control reserve method,reasonable well productivity method,and reasonable gas recovery rate method.Their key parameters were defined,namely the stable production,reasonable gas recovery rate,years of stable production,and unproductive efficiency at the end of stable production period.Moreover,chart regression dependent on analog data was used to figure out value-taking schemes for each key parameters.And through statistical regression and probability analysis,some empirical charts were built for different types of gas reservoirs with various physical properties.Results show that(i)both table and form of statistical regression can be used to quickly determine the above-mentioned key parameters;(ii)the well-control area and unit-thickness well-control reserve methods formed can be used for direct reading and rapid determining well space,and(iii)after the application to a deep-water A gasfield with low permeability in West Africa,the reasonable spacing ranging from 1,000 m to 1,200 m is fixed.These results may offer experiences on the reasonable determination during field development.