The Thin End Of The Test:Operational Procedures For Maximising Successful Formation Pressure Tests While Drilling In Thinly Bedded Sands

摘要

Formation pressure testing while drilling(FPTWD)is an established method of obtaining detailed reservoir pressure data during the drilling process and in operational settings that have very limited formation evaluation alternatives.With many companies,obtaining such data is an integral part of reservoir management strategies,enabling the monitoring of production and injection performance as well assessing reservoir connectivity on a field-wide scale,and in a D frame.FPTWD removes operationally challenging and time-consuming wireline or pipe-conveyed evaluation options that can add unacceptable risk and cost to a project.Obtaining this data as a part of the active drilling phase not only enables a reduction in rig time required for reservoir evaluation,but it also provides an operator valuable information that can impact decisions made on mud weights and casing points while the well is being drilled. FPTWD testing in reservoirs dominated by thin-bedded horizons has traditionally been a hit-and-miss affair,with uncertainties in depth control resulting in a high percentage of tight tests because of pad placement within a shale layer rather than a reservoir horizon.The situation is exacerbated by the automated parameters necessary in a FPTWD tool,whereby tight tests still require the full time interval to complete,but yield no useful pressure information. This paper outlines procedures and techniques successfully applied on turbidite sands in highly deviated wells in deep water fields of Sabah,Malaysia.Utilization of pipe stretch corrections,real-time density images,caliper readings and variations in testing methodology all proved useful in increasing the number of successful tests recorded.By analysing the time required to obtain a valid,three-drawdown test, a reduction of individual test times was made,enabling the decreased overall operational time required.