To understand the extent to which cost reductions are realized and to effectively quantify the size of the potential market for SDO services, it is necessary to understand the basics of the wireline/pressure survey services industry and then contrast traditional methods against the SDO.
Throughout the life of an oil or gas well, many different types of operations are performed, one of which involves reservoir pressure measurement. Within the context of a discussion regarding the benefits of using SDO, the two relevant categories of operations performed on wells are wireline services and "pressure survey services".
Wireline Services
Wireline services involve a wide variety of activities which require the insertion of diagnostic tools in and out of wells on the end of a special cable called "wireline". The wireline is stored, deployed and retrieved from oil, gas and water wells using a winch. Traditional winches are mounted in the back of a truck or trailer for land operations and on a skid for offshore or remote operations to which vehicles don't have access. The wireline service industry is broken down into two broad categories, "logging", and "slickline". Logging involves the use of a type of wireline called "logging cable" )typically 4.8mm to 11.9mm diameter), which contains one or more insulated electrical conductors. The logging cable facilitates the operation and realtime retrieval of data from a wide variety of electrically operated tools and measurement instruments suspended in the well by the logging cable. Slickline wireline services involve the use of a slickline which is smaller in diameter than a logging cable (typically 2.3mm to 3.2mm diameter) and is composed of a solid steel wire without any electrical conductors. Slickline services involve operations which are strictly mechanical in nature.
Pressure Survey Services
Pressure survey services are generally provided by wireline companies. The term "pressure survey" represents a scientific process that specifically involves collecting and analyzing oil and gas reservoir pressure information required by well operators for prudent reservoir management. Reservoirs that require pressure surveys are at least several hundred, and often several thousand metres below the ground. Pressure survey services are most often employed under "well test" conditions. A well test is a temporary scientific procedure that can last from a few hours to several months of duration. In Canada most well tests last between about five and fourteen days. During a well test, the reservoir will flow under controlled conditions at different rates and then it will be shut-in (flow is stopped). The response of the pressure in the reservoir to variable flow rates yields valuable and necessary information about the reservoir and its long term production prospects.
Many different methods are employed to determine oil and gas reservoir pressures. However, all survey methods can be classified as belonging to one or two groups, "surface measurements", or "downhole measurements", plus known and estimated well parameters, become inputs to mathematical functions which calculate the downhole reservoir pressures. Surface measurement survey methods are used mostly to save money. The drawback to surface measurement methods is that resulting low accuracy and quality of the final calculated reservoir pressures. Some regulatory authorities do not recognize the validity of reservoir pressures calculated from surface measurements. When data quality is important, and credible reservoir information is required, the second method, downhole measurement, is preferred. downhole measurement involves lowering very precise electronic instruments into the well on logging cable or slickline and positiong the instruments near the reservoir of interest. RTM's SDO was designed to compete in this second category of well testing procedures.
