Wax-bearing shale oil and gas double-pipe gathering and transportation system and technology

Abstract

The invention relates to the technical field of oil and gas transportation, and discloses a wax-bearing shale oil and gas double-pipe gathering and transportation system and process. According to the system, a double-oil-outlet gathering pipeline is adopted from a well site / platform to a centralized processing station to adapt to full-life-cycle production, high-pressure and low-pressure oil and gas conveying paths are not distinguished in the initial stage of wax-bearing shale oil production, and parallel production of a first oil and gas conveying path and a second oil and gas conveying path adapts to the maximum productivity scale to reach a flat peak; in the wax-bearing shale oil stable production period, oil and gas produced by a high-pressure single well and a low-pressure single well are conveyed in a separated mode, the oil and gas conveying efficiency from a well site / platform to a centralized processing station is improved, a middle two-way communication path is arranged, high-pressure oil and gas are guided into a low-pressure oil and gas conveying path, and the situation that the low-pressure oil and gas conveying path is too low in flow speed and prone to wax precipitation is avoided. The good low-temperature flowing property of the wax-containing shale oil is fully utilized, the purposes of improving the gathering and transportation pipeline efficiency and saving energy consumption are achieved, and energy consumption reduction and cost reduction of the whole life cycle of the wax-containing shale oil gathering and transportation system are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas transportation, and in particular to a waxy shale oil and gas dual-pipe gathering and transportation system and process, which is suitable for the collection and processing of shale oil and gas produced by a large platform well group. Background Art

[0002] At present, foreign shale oil is mainly light oil and condensate oil, while most of the domestic shale oil is heavier medium crude oil and heavy crude oil. For example, the density of Jimusar shale oil in Xinjiang Oilfield is 0.875-0.940g / cm 3 , low pour point, maximum wax content 12.4%. Ordos Basin Changqing Oilfield Qingcheng shale oil density 0.85g / cm 3 The freezing point is low, the viscosity is low, and the gas-oil ratio is 90-110m 3 / t. The density of most shale oil in Jiyang, Shengli Oilfield, Bohai Bay Basin is 0.85-0.91 g / cm 3 , low freezing point and wax content, high gas-oil ratio. The density of Gulong shale oil in Daqing Oilfield, Songliao Basin is 0.8337 g / cm 3 , low viscosity (15.6cp@50℃), pour point 35.8℃, wax content 24% and gas-oil ratio 67m 3 / t. The average density of shale oil in Sinopec Fuxing area is 0.774g / cm 3 , freezing point 24℃, wax content up to 22.4%, and gas-oil ratio average 1000m 3 / t, which is a waxy, high-freezing-point, light shale oil containing condensate gas. The domestic waxy, high-freezing-point shale oil gathering and transportation process usually adopts a single-tube heating or double-tube liquid (oil or water) gathering and transportation process, and the three-tube heating process is rarely used. It is difficult to use normal temperature non-heating transportation or cold transportation gathering and transportation process. At present, the single-tube normal temperature gathering and transportation process has only been realized under high water content and low gas-oil ratio conditions. At present, the main waxy shale oil gathering and transportation processes at home and abroad are:

[0003] 1) Single-pipe oil closed gathering and transportation process

[0004] This waxy shale oil single-pipe gathering and transportation process is used at home and abroad, such as Figure 1 As shown, it is often divided into heating and non-heating gathering and transportation process flows. The reasons are mostly that the physical properties of crude oil are good, the freezing point is near or above the ground temperature, or the natural conditions of the oil field are good, the oil well has a high oil output temperature, a high gas-oil ratio, and a high water content. For example, the freezing point of crude oil in the Qingcheng shale oil field in Changqing is generally around 20°C, and the viscosity is around 4.5mPa.s@50°C. When the water content is greater than 60%, a single-tube non-heating gathering and transportation process is adopted. When it is less than 60%, a platform integrated heating facility is used to ensure that the temperature at the end of the gathering and transportation pipeline is 3°C higher than the freezing point. The single-tube oil outlet heating gathering and transportation process is adopted.

[0005] a. Waxy shale oil single-pipe unheated closed gathering and transportation process, such as Figure 1 Shown

[0006] The gathering and transportation process is from single well - single well metering - oil gathering manifold - centralized processing station. Single well to oil gathering manifold and oil gathering manifold to centralized processing station are all single-pipe oil gathering and transportation. Hot washing interface and ball throwing wax removal facilities are set on the platform oil gathering trunk pipeline. The main technical parameters are maximum oil gathering radius 4.5km, single well production 15t / d, gas-oil ratio 100m 3 / t, crude oil solidification point 20℃, wellhead oil temperature 10~20℃, wellhead oil pressure 1.0~1.5Mpa, gathering and transportation self-consumption gas 5m 3 / t. Advantages: simple system, minimum energy consumption; low investment. Disadvantages: pipeline wax cleaning method uses ball cleaning, which requires daily ball cleaning, heavy operation and management workload; under low temperature conditions, seasonal intermittent heating equipment needs to be turned on to ensure the terminal gathering and transportation temperature.

[0007] b. Single-tube heating and closed gathering and transportation process for waxy shale oil

[0008] The process uses single-tube oil collection, platform heating, centralized metering, and single-tube oil collection trunk pipelines to transport oil and gas to centralized processing stations. The oil and gas from the oil wells (temperature less than 20°C) are first heated by single well selection metering and platform integrated heating equipment, and then enter the centralized processing station through the oil collection trunk line. The wellhead is equipped with a wellbore hot wash interface, the oil collection trunk line outlet pipeline is equipped with a ball-dropping pipe cleaning device, and the oil collection pipeline from the wellhead to the heating furnace is equipped with an electric heating belt for insulation. Main technical parameters: Single well production return period 30m 3 / d~50m 3 / d, water content 100% to 50%; normal production in the first year is 35m 3 / day, water content below 50%; 15m 3 About 30% water content, gas-oil ratio 200m 3 / t, wellhead pressure 0.1MPa~2.0MPa, wellhead oil temperature 10℃~20℃, average oil gathering radius 4~5km, maximum oil gathering radius 8~9km, oil gathering terminal temperature 20~25℃, gas consumption for gathering and transportation less than 10m 3 / t. Advantages: Simple gathering and transportation system, low energy consumption; safe flow in gathering and transportation pipelines. Disadvantages: High investment; complex system.

[0009] The single-pipe gathering and transportation technology is used in the development and application of shale oil in Changqing Oilfield, Xinjiang Oilfield and Shengli Jiyang. It is suitable for the gathering and transportation system from a single well to a centralized processing station. The oil wellhead pressure does not change much, and the gas-oil ratio is within 200m 3 / t of shale oil and gas, there are single-tube gathering and transportation technologies such as single-tube annular and single-tube branch.

[0010] 2) Double-pipe water and liquid mixing (one oil pipeline + one water or liquid mixing pipeline) gathering and transportation technology, such as Figure 2 Shown

[0011] In addition to the single-tube heating process, the Daqing Oilfield Gulong shale oil adopts a double-tube water injection process. This process is mostly a two-level station, namely a metering station and a centralized processing station (oil transfer or dehydration station). There are two pipelines from the wellhead to the centralized processing station, one is the oil gathering pipeline and the other is the water injection pipeline. The gas-liquid separation, sedimentation buffering, dehydration heating and water injection functions are completed in the centralized processing station. Main technical parameters: the water injection outlet temperature is 70°C, the temperature at the end of the gathering and transportation pipeline is 5°C higher than the freezing point of crude oil, the wellhead back pressure is not more than 1.0MPa, and the average single well water injection volume is 1.2m 3 / h~l.5m 3 / h. The oil gathering radius is 2 to 5 km, and the station manages about 100 oil wells, with a maximum of 200.

[0012] Advantages: This process is highly adaptable, safe and reliable for waxy shale oil with high freezing point in severe cold regions. This process is widely used in Daqing Oilfield. Disadvantages: High investment and energy consumption, self-consumption of gas greater than 12m 3 / t oil.

[0013] The waxy shale oil fields currently in production have the following development characteristics: the liquid and oil production are relatively large in the early stage of development, the oil and liquid production in the stable production period are reduced by more than 50% compared with the initial stage, the gas-oil ratio is reduced, the gas production is reduced, the single-tube or double-tube water-blended gathering and transportation process has a large amount of excess capacity in the gathering and output pipelines, the pipeline flow rate is reduced, and the wax deposition rate is increased, which is not conducive to the transportation of waxy shale oil, resulting in a waste of investment. For condensate gas shale oil wells with an initial pressure of more than 20MPa and a later pressure drop to less than 12MPa, the single-tube oil gathering and transportation pipeline is particularly prominent.

[0014] Therefore, in order to improve the efficiency of gathering and transportation pipelines, save energy, make full use of the good low-temperature flow properties of waxy shale oil, and develop a gathering and transportation process with two oil-producing gathering and transportation pipelines for waxy shale oil, it is possible to reduce energy consumption and costs throughout the life cycle of the waxy shale oil gathering and transportation system, which is of great significance to the efficient development of shale oil and gas resources. Summary of the invention

[0015] In view of the above-mentioned defects in the prior art, a waxy shale oil and gas dual-pipe gathering and transportation system and process is provided, which utilizes dual oil gathering and transportation pipelines to meet the production of outputs throughout the entire life cycle from the shale oil wellhead to the centralized processing station, and solves the problems of rapid production decline, short stable production time and large changes in wellhead pressure in shale oil blocks, thereby solving the problems of determining the scale of ground gathering and transportation, and the subsequent rolling development of high and low pressure oil and gas wells on the same platform and oil and gas mixed transportation pipelines.

[0016] The technical solution adopted by the present invention to solve the above technical problems is:

[0017] A waxy shale oil and gas dual-pipe gathering and transportation system includes a well site or platform, and a centralized processing station, and is characterized in that: a first oil and gas transportation path and a second oil and gas transportation path connected in parallel are provided between the well site and the platform, and an intermediate two-way connecting path connecting the first oil and gas transportation path and the second oil and gas transportation path, both ends of the first oil and gas transportation path and the second oil and gas transportation path are respectively connected to the well site or platform, and the centralized processing station; the first oil and gas transportation path and the second oil and gas transportation path are respectively used as high-pressure oil and gas transportation and low-pressure oil and gas transportation, and according to pipeline layout requirements, the first oil and gas transportation path or the second oil and gas transportation path is designated as the path for high-pressure oil and gas transportation; the intermediate two-way connecting path is opened according to demand, and the oil and gas part of the high-pressure oil and gas transportation path is introduced into the low-pressure oil and gas transportation path.

[0018] According to the above technical scheme, a number of single wells are provided in the well site or platform, and the output pipelines of the single wells are connected to the first oil and gas transmission path and the second oil and gas transmission path at the same time; a pressure detector is provided in the output pipeline of each single well, and the single well is selected to be connected to the first oil and gas transmission path or the second oil and gas transmission path according to the oil and gas pressure produced by each single well.

[0019] According to the above technical solution, the first oil and gas transmission path is composed of a plurality of first oil outlet lines, a first oil gathering manifold and a first gathering trunk line. The output pipeline of each single well is connected to a first oil outlet line, and the other end of all the first oil outlet lines is connected to one end of the gathering trunk line through the first oil gathering manifold, and the other end of the first gathering trunk line is connected to the centralized processing station;

[0020] The second oil and gas transmission path is composed of a plurality of second oil outlet lines, a second oil gathering manifold and a second gathering trunk line. The output pipeline of each single well is connected to a second oil outlet line. The other ends of all second oil outlet lines are connected to one end of the gathering trunk line through the second oil gathering manifold. The other end of the second gathering trunk line is connected to a centralized processing station.

[0021] The output pipeline of a single well is connected to the first oil outlet line or the second oil outlet line according to demand, and the intermediate two-way communication path is connected between the first oil collecting manifold and the second oil collecting manifold.

[0022] According to the above technical scheme, valves are provided at the connection between the first oil outlet line and the single well oil outlet pipe, and at the connection between the second oil outlet line and the single well oil outlet pipe. The valves open or close the valves at the connection between the first oil outlet line and the single well oil outlet pipe, and at the connection between the second oil outlet line and the single well oil outlet pipe according to the oil and gas pressure produced by the single well, and the situation of the first oil and gas transmission path and the second oil and gas transmission path transmitting high-pressure or low-pressure oil and gas.

[0023] According to the above technical scheme, a skid-mounted well selection and metering skid is provided at the ends of the first oil gathering manifold and the second oil gathering manifold close to the single well, the first oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the first oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid; the second oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the second oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid.

[0024] According to the above technical scheme, a heating structure and a throttling structure are also provided in the single well output pipeline, and the throttling structure is located after the pressure detector; the heating device is used to heat the output pipeline with a production oil and gas pressure of aMPa and above, where a has a value range of 10 or more, and the throttling device is used to throttle the oil and gas in the output pipeline to reduce the pressure.

[0025] According to the above technical solution, after heating, the temperature of the oil and gas output flowing out of the output pipeline is between 35°C and 45°C; it is necessary to ensure that the inlet temperature of the oil and gas output on the first oil and gas transportation path and the second oil and gas transportation path is controlled to be 3°C higher than the freezing point of shale oil.

[0026] A waxy shale oil and gas dual-pipe gathering and transportation process, characterized in that it comprises the following steps:

[0027] In the initial stage of production, each single well is connected to the closest path between the first oil and gas transmission path and the second oil and gas transmission path;

[0028] Heat the output pipeline of a single well with a production oil and gas pressure greater than aMPa, and adjust the heating temperature so that the temperature of the oil and gas output entering the centralized processing station is 3°C higher than the freezing point of shale oil;

[0029] Throttling of oil and gas output from all single wells, with the pressure after throttling maintained at 4MPa~5MPa;

[0030] During the stable production period, according to the pressure in each single well output pipeline, the optimal oil and gas transmission path is allocated according to the pressure, and the first oil and gas transmission path or the second oil and gas transmission path is set as the high-pressure oil and gas transmission path;

[0031] The output pipeline of a single well with a production oil and gas pressure greater than aMPa is heated, and the heating temperature is adjusted to match the oil and gas introduced from the high-pressure oil and gas transmission path to the low-pressure oil and gas transmission path, so that the temperature of the oil and gas output entering the centralized processing station from the first oil and gas transmission path and the second oil and gas transmission path is 3°C higher than the freezing point of shale oil;

[0032] The oil and gas output of all single wells is throttled, and the pressure of the high-pressure oil and gas transmission path is maintained at 4MPa~5Mpa, and the pressure of the low-pressure oil and gas transmission path is maintained at 1.5MPa~2.0MPa.

[0033] According to the above technical solution, an electric valve is set in the middle two-way connecting path, and pressure sensors are provided in the first oil and gas delivery path and the second oil and gas delivery path. The opening and closing and opening degree of the electric valve are controlled according to the pressure in the low-pressure oil and gas delivery path detected by the pressure sensor.

[0034] The present invention has the following beneficial effects:

[0035] In the early stage of waxy shale oil production, since the oil and gas pressure in each single well is at a relatively high state, the first oil and gas pipeline diameter and the second oil and gas pipeline diameter do not distinguish between high-pressure oil and gas transmission paths and low-pressure oil and gas transmission paths, and the oil and gas produced by each single well are directly transported to the centralized processing station through the nearest first oil and gas transmission path or the second oil and gas transmission path; in the stable production period of waxy shale oil, due to the rapid production decline, short stable production time and large changes in wellhead pressure in shale oil blocks, the production oil and gas pressure of some single wells in the well site gradually fluctuates greatly, and the production oil and gas pressure of a considerable number of single wells is at low pressure. At this time, according to the distribution of all low-pressure wells and the optimal transmission path, the first oil and gas transmission path or the second oil and gas transmission path is selected as the low-pressure oil and gas transmission path, and the remaining path is used as the high-pressure oil and gas transmission path. Subsequently, the medium pressure in the low-pressure oil and gas transmission path is tested. When the pressure is too low, the intermediate two-way connecting path is opened to introduce the oil and gas part of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path. The high-pressure oil and gas are used to disturb the flow of low-pressure shale oil and gas in the low-pressure oil and gas transmission path, avoiding wax deposition and extending the pipe cleaning cycle.

[0036] Based on the above measures, this system adopts dual oil gathering and transportation pipelines from the well site / platform to the centralized processing station to adapt to the production of the whole life cycle. In the early stage of waxy shale oil production, high and low pressure oil and gas transportation paths are not distinguished. The first oil and gas transportation path and the second oil and gas transportation path are produced in parallel to adapt to the maximum production capacity scale to reach the flat peak; in the stable production period of waxy shale oil, the oil and gas produced by high-pressure single wells and low-pressure single wells are separated for production to improve the oil and gas transportation efficiency from the well site / platform to the centralized processing station, and an intermediate two-way connecting path is set to guide high-pressure oil and gas into the low-pressure oil and gas transportation path to avoid the low flow rate of the low-pressure oil and gas transportation path, which is easy to precipitate wax. Taking full advantage of the good low-temperature flow properties of waxy shale oil, it plays the purpose of improving the efficiency of the gathering and transportation pipeline and saving energy consumption, realizing the energy consumption reduction and cost reduction of the whole life cycle of the waxy shale oil gathering and transportation system, which is of great significance to the efficient development of shale oil and gas resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of a single-pipe gathering and transportation process for waxy shale oil in the prior art;

[0038] Figure 2 It is a schematic diagram of a double-pipe water-mixed gathering and transportation process for waxy shale oil in the prior art;

[0039] Figure 3 It is a structural schematic diagram of an embodiment provided by the present invention;

[0040] Figure 4 It is a detailed diagram of an embodiment provided by the present invention;

[0041] In the figure, 1, well site or platform; 1-1, single well; 1-2, output pipeline; 2, centralized processing station; 3, first oil and gas transportation path; 3-1, first oil output line; 3-2, first oil gathering manifold; 3-3, first gathering and transportation trunk line; 4, second oil and gas transportation path; 4-1, second oil output line; 4-2, second oil gathering manifold; 4-3, second gathering and transportation trunk line; 5, intermediate two-way connecting path; 6, skid-mounted well selection and metering skid. DETAILED DESCRIPTION

[0042] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0043] Reference Figure 3-4 As shown, a waxy shale oil and gas dual-pipe gathering and transportation system provided by the present invention includes a well site or platform 1, and a centralized processing station 2, a first oil and gas transportation path 3 and a second oil and gas transportation path 4 connected in parallel are provided between the well site and the platform, and an intermediate two-way connecting path 5 connecting the first oil and gas transportation path and the second oil and gas transportation path is provided, both ends of the first oil and gas transportation path and the second oil and gas transportation path are respectively connected to the well site or platform, and the centralized processing station; the first oil and gas transportation path and the second oil and gas transportation path are respectively used as high-pressure oil and gas transportation and low-pressure oil and gas transportation, and according to the pipeline layout requirements, the first oil and gas transportation path or the second oil and gas transportation path is designated as the path of high-pressure oil and gas transportation; the intermediate two-way connecting path is opened according to demand, and the oil and gas part of the high-pressure oil and gas transportation path is introduced into the low-pressure oil and gas transportation path.

[0044] In this embodiment, in the early stage of waxy shale oil production, since the oil and gas pressure in each single well is at a relatively high state, the first oil and gas pipeline diameter and the second oil and gas pipeline diameter do not distinguish between high-pressure oil and gas transmission paths and low-pressure oil and gas transmission paths, and the oil and gas produced by each single well are directly transported to the centralized processing station through the nearest first oil and gas transmission path or the second oil and gas transmission path; in the stable production period of waxy shale oil, due to the rapid production decay, short stable production time and large changes in wellhead pressure in shale oil blocks, the production oil and gas pressure of some single wells in the well site gradually fluctuates greatly, and the production oil and gas pressure of a considerable number of single wells is at low pressure. At this time, according to the distribution of all low-pressure wells and the optimal transmission path, the first oil and gas transmission path or the second oil and gas transmission path is selected as the low-pressure oil and gas transmission path, and the remaining path is used as the high-pressure oil and gas transmission path. Subsequently, the medium pressure in the low-pressure oil and gas transmission path is tested. When the pressure is too low, the intermediate two-way connecting path is opened to introduce the oil and gas part of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path. The high-pressure oil and gas are used to disturb the flow of low-pressure shale oil and gas in the low-pressure oil and gas transmission path, avoiding wax deposition and extending the pipe cleaning cycle.

[0045] Based on the above measures, this system adopts dual oil gathering and transportation pipelines from the well site / platform to the centralized processing station to adapt to the production of the whole life cycle. In the early stage of waxy shale oil production, high-pressure and low-pressure oil and gas transportation paths are not distinguished. The first oil and gas transportation path and the second oil and gas transportation path are produced in parallel to adapt to the maximum production capacity scale to reach the flat peak; in the stable production period of waxy shale oil, the oil and gas produced by high-pressure single wells and low-pressure single wells are separated for production to improve the oil and gas transportation efficiency from the well site / platform to the centralized processing station, and an intermediate two-way connecting path is set to introduce the high-pressure oil and gas part into the low-pressure oil and gas transportation path to avoid the low flow rate of the low-pressure oil and gas transportation path. Waxy shale oil has good low-temperature flow properties, which can improve the efficiency of the gathering and transportation pipeline and save energy consumption, and achieve energy consumption and cost reduction in the whole life cycle of the waxy shale oil gathering and transportation system, which is of great significance to the efficient development of shale oil and gas resources.

[0046] Example 2

[0047] The structure and principle of Example 2 are similar to those of Example 1, except that a layout of a high-pressure oil and gas transmission path and a low-pressure transmission path is provided, and the selection of the transmission path is determined by the distribution position of the oil and gas output of a single well in a well site or platform in a low-pressure state.

[0048] Specifically, a number of single wells 1-1 are provided in the well site or platform, and the output pipelines of the single wells are connected to the first oil and gas transmission path and the second oil and gas transmission path at the same time; a pressure detector is provided in the output pipeline 1-2 of each single well, and the single well is selected to be connected to the first oil and gas transmission path or the second oil and gas transmission path according to the oil and gas pressure produced by each single well.

[0049] Example 3

[0050] The structure and principle of Example 3 are similar to those of Example 2, except that a preferred arrangement of the first oil and gas delivery path and the second oil and gas delivery path is provided.

[0051] The first oil and gas transmission path is composed of a plurality of first oil outlet lines 3-1, a first oil gathering manifold 3-2 and a first gathering trunk line 3-3. The output pipeline of each single well is connected to a first oil outlet line, and the other end of all first oil outlet lines is connected to one end of the gathering trunk line through the first oil gathering manifold, and the other end of the first gathering trunk line is connected to the centralized processing station;

[0052] The second oil and gas transmission path is composed of a plurality of second oil outlet lines 4-1, a second oil gathering manifold 4-2 and a second gathering trunk line 4-3. The output pipeline of each single well is connected to a second oil outlet line, and the other end of all the second oil outlet lines is connected to one end of the gathering trunk line through the second oil gathering manifold, and the other end of the second gathering trunk line is connected to the centralized processing station;

[0053] The output pipeline of a single well is connected to the first oil outlet line or the second oil outlet line according to demand, and the intermediate two-way communication path is connected between the first oil collecting manifold and the second oil collecting manifold.

[0054] In this embodiment, the output pipeline of each single well is connected to the first oil outlet pipe and the second oil outlet pipe at the same time, and a plurality of first oil outlet pipes and second oil outlet pipes are provided to connect all the single wells to the first gathering and transportation trunk line and the second gathering and transportation trunk line.

[0055] In the above-mentioned embodiment 3, valves are provided at the connection between the first oil outlet line and the single-well oil outlet pipe, and at the connection between the second oil outlet line and the single-well oil outlet pipe. The valves open or close the valves at the connection between the first oil outlet line and the single-well oil outlet pipe, and at the connection between the second oil outlet line and the single-well oil outlet pipe according to the oil and gas pressure produced by the single well, and the situation of the first oil and gas transmission path and the second oil and gas transmission path transmitting high-pressure or low-pressure oil and gas.

[0056] In the above-mentioned embodiment 3, a skid-mounted well selection and metering skid 6 is provided at the ends of the first oil collecting manifold and the second oil collecting manifold near the single well, the first oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, the first oil collecting manifold is connected to the outlet of the skid-mounted well selection and metering skid; the second oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, the second oil collecting manifold is connected to the outlet of the skid-mounted well selection and metering skid. In this embodiment, the skid-mounted well selection and metering skid adopts a detachable structure.

[0057] Example 4

[0058] The structure and principle of Example 4 are similar to those of Example 2, except that: to facilitate the transportation of oil and gas output, the oil and gas output above the set pressure is heated, and all oil and gas output is throttled and depressurized.

[0059] Specifically, a heating structure and a throttling structure are provided in the single well output pipeline, and the throttling structure is located after the pressure detector; the heating device is used to heat the output pipeline with a production oil and gas pressure of aMPa and above, where a has a value range of 10 or more, and the throttling device is used to throttle the oil and gas in the output pipeline to reduce the pressure.

[0060] In Example 4, after heating, the temperature of the oil and gas output flowing out of the output pipeline is between 35°C and 45°C; it is necessary to ensure that the inlet temperature of the oil and gas output on the first oil and gas transportation path and the second oil and gas transportation path is controlled to be 3°C higher than the freezing point of shale oil.

[0061] The present invention also provides a waxy shale oil and gas dual-pipe gathering and transportation process, comprising the following steps:

[0062] In the initial stage of production, each single well is connected to the closest path between the first oil and gas transmission path and the second oil and gas transmission path;

[0063] Heat the output pipeline of a single well with a production oil and gas pressure greater than aMPa, and adjust the heating temperature so that the temperature of the oil and gas output entering the centralized processing station is 3°C higher than the freezing point of shale oil;

[0064] The oil and gas output of all single wells is throttled, and the pressure after throttling is maintained at 4MPa~5MPa.

[0065] During the stable production period, according to the pressure in each single well output pipeline, the optimal oil and gas transmission path is allocated according to the pressure, and the first oil and gas transmission path or the second oil and gas transmission path is set as the high-pressure oil and gas transmission path;

[0066] The output pipeline of a single well with a production oil and gas pressure greater than aMPa is heated, and the heating temperature is adjusted to match the oil and gas introduced from the high-pressure oil and gas transmission path to the low-pressure oil and gas transmission path, so that the temperature of the oil and gas output entering the centralized processing station from the first oil and gas transmission path and the second oil and gas transmission path is 3°C higher than the freezing point of shale oil;

[0067] The oil and gas output of all single wells is throttled, and the pressure of the high-pressure oil and gas transmission path is maintained at 4Mpa~5Mpa, and the pressure of the low-pressure oil and gas transmission path is maintained at 1.5MPa~2.0MPa.

[0068] In this process, preferably, an electric valve is provided in the middle two-way communication path, and pressure sensors are provided in both the first oil and gas delivery path and the second oil and gas delivery path, and the opening and closing and opening degree of the electric valve are controlled according to the pressure in the low-pressure oil and gas delivery path detected by the pressure sensor. When the flow rate is too low, the pressure of the first oil and gas delivery path or the second oil and gas delivery path as the low-pressure oil and gas delivery path will increase, so the change in flow rate is detected by the pressure sensor.

[0069] Working principle of the present invention:

[0070] From a single well / platform to a centralized processing station, dual-outlet oil gathering and transportation pipelines are used to accommodate production throughout the entire life cycle; initial parallel production is used to adapt to the maximum production capacity scale to reach peak levels, and different pressures are used for production during the stable production period to improve pipeline transportation efficiency and avoid wax precipitation due to low flow rates; through the intermediate two-way connecting path between the first oil and gas transportation path and the second oil and gas transportation path, high-pressure oil and gas are controlled to enter the low-pressure pipeline, disturbing the flow of low-pressure shale oil and gas to avoid wax deposition and prolonging the pipe cleaning cycle.

[0071] The above are only preferred embodiments of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the protection scope of the present invention.

Claims

1. A waxy shale oil and gas dual-pipe gathering and transportation system, comprising a well site or platform, and a centralized processing station, characterized in that: A first oil and gas transmission path and a second oil and gas transmission path connected in parallel with each other, and an intermediate two-way connecting path connecting the first oil and gas transmission path and the second oil and gas transmission path are provided between the well site and the platform. Both ends of the first oil and gas transmission path and the second oil and gas transmission path are respectively connected to the well site or the platform and the centralized processing station; the first oil and gas transmission path and the second oil and gas transmission path are respectively used as high-pressure oil and gas transmission and low-pressure oil and gas transmission. According to the requirements of pipeline layout, the first oil and gas transmission path or the second oil and gas transmission path is designated as the path of high-pressure oil and gas transmission; the intermediate two-way connecting path is opened according to the requirements to guide the oil and gas part of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path.

2. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 1 is characterized by: A number of single wells are arranged in the well site or platform, and the output pipelines of the single wells are connected to the first oil and gas transmission path and the second oil and gas transmission path at the same time; a pressure detector is arranged in the output pipeline of each single well, and the single well is selected to be connected to the first oil and gas transmission path or the second oil and gas transmission path according to the oil and gas pressure produced by each single well.

3. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 2 is characterized by: The first oil and gas transmission path is composed of a plurality of first oil outlet lines, a first oil gathering manifold and a first gathering trunk line, the output pipeline of each single well is connected to a first oil outlet line, the other end of all the first oil outlet lines is connected to one end of the gathering trunk line through the first oil gathering manifold, and the other end of the first gathering trunk line is connected to a centralized processing station; The second oil and gas transmission path is composed of a plurality of second oil outlet lines, a second oil gathering manifold and a second gathering trunk line. The output pipeline of each single well is connected to a second oil outlet line. The other ends of all second oil outlet lines are connected to one end of the gathering trunk line through the second oil gathering manifold. The other end of the second gathering trunk line is connected to a centralized processing station. The output pipeline of a single well is connected to the first oil outlet line or the second oil outlet line according to demand, and the intermediate two-way communication path is connected between the first oil collecting manifold and the second oil collecting manifold.

4. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 3 is characterized by: Valves are provided at the connection between the first oil outlet line and the single well oil outlet pipe, and at the connection between the second oil outlet line and the single well oil outlet pipe. The valves open or close the valves at the connection between the first oil outlet line and the single well oil outlet pipe, and at the connection between the second oil outlet line and the single well oil outlet pipe according to the oil and gas pressure produced by the single well, and the situation of the first oil and gas transmission path and the second oil and gas transmission path transmitting high-pressure or low-pressure oil and gas.

5. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 3 is characterized by: A skid-mounted well selection and metering skid is provided at the ends of the first oil gathering manifold and the second oil gathering manifold close to the single well. The first oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the first oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid; the second oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the second oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid.

6. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 2 is characterized by: A heating structure and a throttling structure are also provided in the single well output pipeline, and the throttling structure is located after the pressure detector; the heating device is used to heat the output pipeline with a production oil and gas pressure of aMPa and above, where a has a value range of 10 or more, and the throttling device is used to throttle the oil and gas in the output pipeline to reduce the pressure.

7. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 6 is characterized by: After heating, the temperature of the oil and gas output flowing out of the output pipeline is between 35°C and 45°C; it is necessary to ensure that the inlet temperature of the oil and gas output of the first oil and gas transportation path and the second oil and gas transportation path is controlled to be 3°C higher than the freezing point of shale oil.

8. A waxy shale oil and gas dual-pipe gathering and transportation process, characterized by: The steps include: In the initial stage of production, each single well is connected to the closest path between the first oil and gas transmission path and the second oil and gas transmission path; Heat the output pipeline of a single well with a production oil and gas pressure greater than aMPa, and adjust the heating temperature so that the temperature of the oil and gas output entering the centralized processing station is 3°C higher than the freezing point of shale oil; Throttling of oil and gas output from all single wells, with the pressure after throttling maintained at 4MPa~5MPa; During the stable production period, according to the pressure in each single well output pipeline, the optimal oil and gas transmission path is allocated according to the pressure, and the first oil and gas transmission path or the second oil and gas transmission path is set as the high-pressure oil and gas transmission path; The output pipeline of a single well with a production oil and gas pressure greater than aMPa is heated, and the heating temperature is adjusted to match the oil and gas introduced from the high-pressure oil and gas transmission path to the low-pressure oil and gas transmission path, so that the temperature of the oil and gas output entering the centralized processing station from the first oil and gas transmission path and the second oil and gas transmission path is 3°C higher than the freezing point of shale oil; The oil and gas output of all single wells is throttled, and the pressure of the high-pressure oil and gas transmission path is maintained at 4MPa~5Mpa, and the pressure of the low-pressure oil and gas transmission path is maintained at 1.5MPa~2.0MPa.

9. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 8, characterized in that: An electric valve is set in the middle two-way connecting path, and pressure sensors are provided in the first oil and gas transmission path and the second oil and gas transmission path. The opening and closing and opening degree of the electric valve are controlled according to the pressure in the low-pressure oil and gas transmission path detected by the pressure sensor.

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