白马庙蓬莱镇气藏生产效果影响因素分析

INFLUENTIAL FACTORS OF PRODUCTION PERFORMANCE OF PENGLAIZHEN FM GAS POOL IN BAIMAMIAO AREA

白马庙蓬莱镇组气藏是目前川西南部储量最大的浅层气藏,储层致密,孔隙结构复杂,非均质性强,单井产能低、递减快。深化储层特征、气井生产效果主控因素及增产措施的研究是气藏高效开发的出路。研究与实践表明,储集系数(Hφ)越大,气井产能越高,递减越慢。白浅26、38井等9口高、中产井均钻在主河道砂体上,获气井成功率100%,平均气产量是其它相带的4.3倍。针对储层低孔渗、强水敏、强水锁特点,采用欠平衡或天然气钻井技术,缩短了钻井周期,减低了污染,解放了产层;加强合理配产研究,增长了稳产期。全气藏加砂压裂42井次,压裂成功率达71.43%,无阻流量增加85.53×104m3/d;采用同井场大斜度井或水平井钻井技术,充分暴露和解放了气层,节省了井场投资,其无阻流量与同井场直井相比增大了18倍,且投产后生产效果明显改善。

Penglaizhen Fm gas pool in Baimamiao area is by now the largest shallow gas accumulation in respect of gas reserves in southwest of Sichuan basin and is characterized by tight reservoir, complex pore structure, strong heterogeneity, low single well deliverability and steep decline of single well production. Study of reservoir characteristics, the main control factors of gas well production performance and well stimulation should be strengthened, so as to efficiently develop the gas pool. Both study and practice show that gas well deliverability increases and its decline rate lowers along with the increasing reservoir capacity (Hφ). All the nine gas producers with high to medium production capacities, including Baiqian 26 and 38 wells, are positioned on the main channel sandbody and the success ratio of production tests is 100%. Their average gas production is 4.3 times that of gas wells located in other facies belts. In view of the reservoir characteristics of low porosity and low permeability and strong water sensitivity, under-balanced and gas drilling technologies are used to shorten the drilling time, lessen formation damage and liberate pay zones. Study of rational production proration is strengthened to prolong the production plateau. Full-reservoir sand fracturing, with a success ratio of 71.43%, was performed in 42 wells/times, resulting in an incremental AOF of 855,300 m3/d. Highly-deviated wells and horizontal wells are drilled in a common well site to fully expose and liberate the gas reservoir and to lower well site investment. There is a 18-fold increase in the AOF compared with the vertical wells in the same well site and the production performances are remarkably improved after they are brought on line.