The main flow of oil and gas field exploration and development: geological exploration — geophysical exploration — drilling — logging — logging — cementing — completion — perforating — production — workover — additional production — transportation — processing, etc.These links are interrelated and inseparable. As professional oilmen, it is necessary for us to have a global understanding of the process of oil exploration and development.
1. geological exploration
Geological exploration means that petroleum exploration personnel use geological knowledge, carry simple tools such as compass and hammer, and understand sedimentary strata and structural characteristics by directly observing and studying the substratum and rocks exposed on the ground in the field.Collect all geological data in order to find out the favorable zones and distribution rules of oil and gas generation and accumulation so as to find oil and gas fields.However, most of the earth’s surface is covered by recent deposits, which limits geological exploration.The process of geological exploration is indispensable, which greatly reduces the area of work to be carried out in the next geophysical exploration and saves costs.
The ground geological survey method is generally divided into three steps: general survey, detailed survey and detailed survey.The basic map is called a geological map, and it identifies areas and areas of interest for detailed exploration.Detailed investigation is mainly embodied in “selection”, which further confirms the promising areas of the census to select more powerful oil-bearing structures.The fine survey is mainly reflected in the “fixed”, which selects the structure, determines the oil-bearing structure through the fine survey, and works out the accurate structure map for further drilling. The purpose is to find the oil and gas field as soon as possible.
2. Seismic exploration
Reflection seismic method is an important method in geophysical exploration.Seismic exploration is a method of surveying underground geological conditions by using the propagation law of seismic waves generated by artificial excitation in different elastic strata.Seismic wave in the process of underground transmission, local rock layer of elastic parameters change, thus cause changes in seismic wave field, and reflection, refraction and transmission phenomenon, through the artificial seismic waves, after receiving change after data processing and interpretation to the performance of the underground geological structure and lithology, geological prospecting.Seismic exploration methods can be divided into reflection wave method, refraction wave method and transmission wave method.
3 steps of seismic exploration:
The first step is field acquisition.The task of this link is to lay out survey lines in the promising oil and gas exploration areas preliminarily determined by geological work and other geophysical exploration work, stimulate seismic waves artificially, and record the propagation of seismic waves with field seismograph.The result of this phase is to obtain the digital “magnetic tape” recording the ground vibration, and the organization form of field production is the earthquake team.Field production is divided into test stage and production stage, the main content is to stimulate seismic waves, receiving seismic waves.
The second step is indoor data processing.The task of this link is to process all kinds of raw data obtained in the field, and the result is “seismic profile” and seismic wave velocity, frequency and other data.
The third part is the interpretation of seismic data.The task of this link is to use the theory of seismic wave propagation and the principle of petroleum geology, comprehensive geological, drilling data, in-depth analysis and research on the seismic profile, explain the lithology and geological age of the strata, explain the characteristics of underground geological structure;Drawing the structure map of some main layers and other comprehensive analysis map;To find out the traps which contain oil and gas and put forward the drilling location.
After the exploration of petroleum workers will find the oil storage block, using special equipment and technology, in the pre-selected surface location, down or side drilling a certain diameter cylindrical hole, and drilling underground oil and gas layer work, known as drilling.
Drilling plays a very important role in various tasks of petroleum exploration and oilfield development.Such as finding and verifying petroliferous structures, obtaining industrial oil flows, finding and verifying the petroliferous areas and reserves of petroliferous structures, obtaining geological data and development data of oil fields, and finally bringing crude oil from underground to the surface, etc., are all accomplished through drilling.Drilling is an important link of exploration and exploitation of oil and natural gas resources, and an important means of exploration and exploitation of oil.
The process of oil exploration and development consists of many stages with different natures and tasks.In different stages, the purpose and task of drilling are also different.Some are for exploring oil storage structures, others for developing oil fields and extracting crude oil.In order to adapt to the needs of different stages and tasks,
Types of drilling can be divided into the following types:
1) reference Wells: Wells drilled in order to understand the sedimentary characteristics and oil and gas content of strata, verify the geophysical exploration results and provide geophysical parameters during the regional census.Bedrock is usually drilled and full well coring is required.
2) profile well: the well drilled along the regional large profile in the covered area.The purpose is to reveal the regional geological profile, study the stratigraphic lithology and lithofacies changes, and look for structures.Mainly used in the regional census stage.
3) parameter Wells: Wells drilled in oil-bearing basins to understand regional structures and provide petrophysical parameters are mainly used for comprehensive detailed survey.
4) structural Wells: Wells drilled in order to compile the structural map of a certain underground standard layer, understand its geological structure characteristics, and verify the geophysical exploration results.
5) exploration well: the well drilled to determine the existence of oil and gas reservoirs, to delineate the boundaries of oil and gas reservoirs, to carry out industrial evaluation of oil and gas reservoirs and to obtain the geological data needed for oil and gas development within the scope of favorable oil-gathering structures or oil and gas fields.The Wells drilled in each exploration stage can be divided into pre-exploration Wells, preliminary exploration Wells and detailed exploration Wells.
6) data well: the well drilled for the purpose of compiling the development plan of oil and gas field or obtaining data for some special research in the development process.
7) production well: the well drilled to extract oil and gas during oilfield development.Production Wells can be divided into production Wells and gas Wells.
8) water injection (gas) well: a well drilled by injecting water and gas into an oil field to supplement and reasonably utilize formation energy in order to improve recovery and development speed.The Wells drilled for water injection and gas injection are called injection Wells or gas injection Wells, sometimes collectively referred to as injection Wells.
9) inspection Wells: Wells drilled in order to find out the pressure, oil, gas and water distribution of each oil layer, the distribution and change of remaining oil saturation, as well as the effect of various adjustment and potential exploration measures at a certain water-cut stage of oilfield development.
10) Observation well: a well designed to understand the underground dynamics of an oilfield during its development.Such as observation of various types of reservoir pressure, water cut changes and single layer of water flooded law!It generally does not undertake production tasks.
11) adjustment Wells: Wells drilled in the original development well pattern (including production Wells, injection Wells, observation Wells, etc.) in the middle and later stages of oilfield development to further improve the development effect and ultimate recovery.The reservoir pressure in such Wells may be low due to late production or high due to the energy retained by the injector.
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