Drill stem test/DST, also known as oil and gas reservoir testing or formation testing, refers to the testing of oil-producing capacity, fluid properties and reservoir characteristics of possible oil and gas reservoirs. DST is the key to oil and gas exploration and reservoir understanding. It is a means to submit geological reports and obtain important data for well exploration. Before testing the oil and gas, clean water should be used to wash the well and circulate slurry,The data were recorded when the oil flow was stable.

Testing of oil and gas after completion of the well.High-pressure oil or gas flow, or oil well with large output, is first injected, and then different nozzles of different diameters are changed in the oil production tree. In several long stable periods, data of oil and gas flow and pressure changes can be tested, and maximum output and production index (i.e., production capacity) can be calculated.The physical properties and chemical composition of oil, gas and water can be obtained by sampling and analyzing.

Low pressure oil layer and small production of oil Wells, clean water after mud, can be adopted by gas lift.It is to use air duct of compressed air to put in annular air pressure gas, and take the liquid out of the oil pipe to lower the fluid level in the well, so that oil and gas flow into the well, and then flow out from the oil pipe, recording the flow rate and the height of oil level in the well.It is also possible to test the oil with the method of lifting and fishing, extract the oil from the well with the lifting barrel, test the height of the oil level and calculate the output.Or with the steel rope pull the extraction, swabbing induced jet.Formal oil recovery is to set pumping unit, pull pump for testing.

Significance:

The importance of stratified testing is also reflected in that the oil testing data obtained is the data under the original reservoir conditions, such as the original formation pressure, the initial production and original water content of the well, the original effective permeability of the reservoir and the early property of oil and gas.If these data are missed or unqualified, they cannot be remedied after the reservoir is put into development.Moreover, the oil test can be conducted in small or single layers according to the needs and the separation conditions, and valuable single-layer productivity, pressure and permeability data can be obtained, which is extremely valuable for the understanding of inter-layer heterogeneity, the combined development of stratigraphic series, the formulation of injection and production plan and the research on remaining oil.It is very difficult to obtain accurate and reliable stratification data when multiple reservoirs are combined with each other after development.

Good DST job can find oil and gas fields in time and realize the basic purpose of oil and gas searching.But if the work is not done well, the discovery of oil and gas fields may be delayed or even missed.Such cases are not unique. For example, the discovery of the daqing oilfield has been attributed to oil testing.The discovery well of daqing oil field is well songji 3, which is designed with a depth of 3,200m. Oil-soaked sandstones were found in the qingshankou formation of the white seal system, and the mud returned crude oil and gas bubbles were found twice during the drilling. With the consent of the oil ministry, the oil was drilled in advance at 1461.76m.In September 1959, three thin oil layers of the qingshankou group from 1357.01 to 1382.44m were first shot out in September, 1959. Thus Daqing oildield was discovered:the world - class super - large oil and gas field.