Horizontal Coalbed Methane Wells Drilled with MPD using Produced Water

摘要

Horizontal drilling in the Fruitland Formation,a Coalbed Methane(CBM)play located in the San JuanBasin(SJB),found across the states of Colorado and New Mexico can present a number of drilling andproduction challenges.Examples of these challenges include wellbore instability,severe fluid losses,highmud costs,formation damage,and post-well production issues.Clear fluid brine systems such as Calcium Chloride(CaCl2)and Calcium Bromide(CaBr2)are usuallypreferred because of their compatibility with coals and their ability to minimize formation damage.However,these brines can instigate fluid losses,cause fluid handling issues,and create long-term productionchallenges.Coal instability in the horizontal play has historically led to events such as wellbore collapse,stuck pipe,lost Bottomhole Assemblies(BHAs),and challenges such as getting the pipe out of the holeat Total Depth(TD)and subsequently running completions.Ultimately,these problems led to sidetracks,incurring additional costs,time,and resources.In May 2019,the Constant Bottomhole Pressure(CBHP)technique of Managed Pressure Drilling(MPD)was introduced to mitigate these challenges.Two wells with eight laterals and combined horizontal footageof ±46,000 ft were drilled using CBHP,maintaining 11.4 ±0.1 pound per gallon(ppg)Equivalent CirculatingDensity(ECD)and Equivalent Static Density(ESD)in the lateral at ±2800 ft True Vertical Depth(TVD).With a focus on safety and training,the mud weight was staged down from 10.8 ppg on the first lateral to9.8 ppg on the second.The final six laterals were drilled with 8.6 ±0.2 ppg produced water.This paper willdetail the planning,training and staged implementation of CBHP MPD with produced water.It will brieflydiscuss improvement in wellbore stability,cost reduction for drilling laterals,and enhanced production afterswitching to produced water.