CN-115876828-B - Detection method for determining wall-sticking oil-solidifying formation temperature in high-water-content oil collecting pipeline

CN115876828BCN 115876828 BCN115876828 BCN 115876828BCN-115876828-B

Abstract

The invention belongs to the field of crude oil gathering and transportation, and discloses a detection method for determining the formation temperature of wall-sticking oil condensate in a high-water-content oil collecting pipeline. The method can more accurately test the formation temperature of the oil condensation wall sticking in the high-water-content oil collecting pipeline, and is helpful for more accurately researching the boundary temperature of the unheated oil collecting pipeline. The invention also provides a detection system for determining the formation temperature of the wall-sticking oil-condensing layer in the high-water-content oil-collecting pipeline, the detection system prefabricates the wall-sticking oil-condensing layer in the test pipe section through a die, and constructs a loop through a peristaltic pump, a flowmeter and a connecting pipeline, so that the stress condition of the wall-sticking oil-condensing layer in the detection system is more similar to the actual condition of the pipeline transportation. And by observing the form of the flushed oil, whether the oil is peeled off from the pipe wall or not can be conveniently and accurately judged, and the formation temperature of the wall-sticking oil can be further obtained.

Inventors

MA XIAOHONG
DING LEI
WANG CONG
HAN SHANPENG
CHENG GUOJUN
FU TIANBO
GAO JUN
GAO WENLIN
SONG ZHENGKAI
Huang Hehao

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20210927

Claims (10)

1. The detection method for determining the formation temperature of the wall-sticking oil condensate in the high-water-content oil collecting pipeline is characterized by comprising two links, namely (1) a loop preparation link and (2) a loop experiment link; (1) The method comprises the steps of firstly prefabricating a congealing layer on the inner wall of a test pipe section provided with a temperature control interlayer, then connecting the test pipe section into a test loop, adjusting a temperature control water bath connected with the temperature control interlayer of the test pipe section to enable the temperature of circulating water to reach T 1 and be lower than the congealing point of crude oil; (2) Setting the temperature of circulating water in a temperature control water tank to be T 1 , starting a peristaltic pump after the water temperature reaches a preset value, setting the flow rate to be Q 1 , setting the flow rate to be v 1 , starting flushing a wall-sticking oil layer, observing the form of the oil layer by flushing liquid flow, spreading the oil in the temperature control water tank in a ' continuous deformation ' state at the temperature of T 1 , namely Q 1 、v 1 、T 1 , enabling the oil layer to be stripped from the pipe wall in a yielding and continuous deformation mode, namely ' oil sticking ' does not occur, and then needing to perform a second group of experiments, reducing the circulating water temperature of the temperature control water bath to be T 2 ,T 2 <T 1 , repeating the loop preparation link, setting the circulating water temperature in the temperature control water tank to be T 2 , and performing the loop experiments again, and if the oil in the temperature control water tank is still in the ' continuous deformation ' state, reducing the temperature of the temperature control water bath and the circulating water layer in the temperature control water tank to be T 3, T 3 <T 2 <T 1 again, and performing experiments again until an ' oil plug ' is found at the tail end of the test pipeline ', namely that the oil sticking between the liquid flow and the wall is not overcome; T 3 is the formation temperature of wall-sticking oil condensation of the oil collecting pipeline under the condition Q 1 、v 1 , under the condition, the wall-sticking oil condensation and the pipe wall of the test pipe section can be stripped under the flushing action of liquid flow, so that an oil condensation plug is easy to form, the pressure drop of the conveying pipe section is quickly increased, the risk of pipe explosion exists, and the lowest safe conveying temperature of the oil collecting pipeline is T 3 .
2. The detection method for determining the formation temperature of the wall-sticking oil condensate in the high-water-content oil collecting pipeline according to claim 1, wherein the length of the test pipe section is 400mm, the inner diameter is 19 mm, the length of the test pipe section covering the temperature control interlayer is 300mm, the diameter of a long rod of the wall-sticking oil condensate manufacturing mould is 8mm, and the thickness of the prefabricated wall-sticking oil condensate layer is 5.5mm.
3. The detection method for determining the formation temperature of the wall-sticking oil in the high-water-content oil collecting pipeline according to claim 2, wherein the peristaltic pump outputs in a constant flow mode, the flow is adjustable, and the flow range is 10-300L/h.
4. The detection method for determining the formation temperature of wall-sticking oil in a high-water-content oil collecting pipeline according to claim 3, wherein the installation position of the test pipe section is 20cm higher than the water surface of circulating water in the temperature control water tank, and the temperature control water tank, the peristaltic pump, the flowmeter and the temperature control water bath are arranged on the same platform.
5. The method for determining the formation temperature of wall-sticking and oil-condensing in a high-water-content oil-collecting pipeline according to claim 4, wherein the test pipe section is provided with a temperature-controlling interlayer, and a temperature-controlling water bath is connected with the temperature-controlling interlayer of the test pipe section to form a closed loop I; and connecting circulating water in the temperature control water tank with the peristaltic pump, the flowmeter and the test tube section to form a closed loop II.
6. A detection system for realizing the detection method as set forth in claim 1, wherein the detection system at least comprises a temperature control water tank, a peristaltic pump, a flowmeter, a temperature control water bath, a test pipe section and a mold for adhering to a wall and solidifying an oil layer.
7. The detecting system according to claim 6, wherein the mold for the wall-sticking oil-solidifying layer comprises a smooth hard plastic long rod with a sealing rubber stopper at an end portion and a funnel, an annular space is formed between an inner wall surface of the test tube section and an outer wall surface of the mold by inserting the mold into the test tube section, crude oil is injected into the annular space through the funnel, and the crude oil is adhered to the tube wall after being gelled under the action of circulating water cooling, so that the wall-sticking oil-solidifying layer is formed.
8. The detecting system according to claim 7, wherein the test tube section with the inner wall attached with the gel layer is connected to a loop system, the loop system is characterized in that an inlet end of the test tube section is connected with an outlet of the flowmeter through a connecting pipe, an outlet end of the test tube section is led out through the connecting pipe and is connected to a liquid level of the temperature control water tank, and the temperature control water tank, the peristaltic pump, the flowmeter and the test tube section are sequentially connected to form an experimental loop.
9. The detecting system according to claim 8, wherein the test tube section is provided with a temperature control interlayer, the temperature control water bath is connected with the temperature control interlayer of the test tube section to form a closed loop I, and the circulating water in the temperature control water tank is connected with the peristaltic pump, the flowmeter and the test tube section to form a closed loop II.
10. The inspection system of claim 9 wherein the temperature control water tank has a power greater than 1.5kW and is an open water tank and the connecting tube is PVC.

Description

Detection method for determining wall-sticking oil-solidifying formation temperature in high-water-content oil collecting pipeline Technical Field The invention belongs to the field of crude oil gathering and transportation, and relates to a detection method for determining the formation temperature of wall-sticking oil condensate in a high-water-content oil collecting pipeline. Background As the field enters the end of development, the significant presence of produced water continues to deteriorate the economics of the "well-spiked water gathering and transportation" process scheme formed in the early stages of development. At the same time, the whole fluidity of the produced liquid is improved, so that the water mixing temperature is reduced, and even the oil collection is not heated. However, the flowing form of the fluid in the pipeline is more complex under the low temperature condition, a conveying form that the gel block is suspended in water is formed, a phenomenon of 'gel sticking to the wall' is generated, the flow area in the pipeline is reduced, the aggregation of the gel block is easily formed at the position of reduced pipe diameter, and a 'gel plug' is formed, so that the pressure drop of the pipeline is rapidly increased. Thus, grasping the formation temperature of "wall-sticking oil-condensing" and controlling the delivery temperature above this temperature is one of the key technologies that does not heat the oil collection. The key of the detection simulation of the formation temperature of the wall-sticking oil condensate in a laboratory is to construct a temperature field and a flow field which are consistent with the actual pipe flow condition, and simulate the adhesion of the oil condensate on the pipe wall and the peeling of the wall-sticking layer from the pipe wall under the action of liquid flow scouring force. The existing detection and research methods for the formation temperature of the wall-sticking oil mainly comprise a condensation point test tube method, a loop method and a cold finger method. The gel point test tube method uses the standard of crude oil gel point test to test the sample, the upper layer in the tube is gelled water-in-oil emulsion, the lower layer is free water, and the gel structure is destroyed by shearing the free water through the inclined test tube. As the temperature decreases, the temperature at which the liquid level in the tube no longer flows is referred to as the "stagnation point". The "stagnation point" reflects to some extent the competition of the yield stress of the gelled oil with the shearing action of the free water. This "stagnation point" is used in some documents as the formation temperature of "wall-sticking oil". However, the method simulates the stress condition of the wall-sticking layer in the pipe transportation process by the gravity of the free water at the lower layer in the test tube, ignores the impact force of the fluid in the actual pipe flow on the oil condensation layer, and has larger difference with the actual condition. The indoor loop experiment adopts a similar principle to simulate the flow characteristics of an actual pipe, and the experimental method is widely applied, and the components comprise a stirring tank, a peristaltic pump, a flowmeter, a pressure gauge, a temperature-control water bath and the like. The wall sticking phenomenon at different oil flow temperatures is simulated by adopting an annular circuit, wherein the temperature at which the pressure drop of the test pipe section is obviously increased is generally defined as the wall sticking temperature, and the temperature is taken as the non-heating oil collecting temperature limit. However, the high water-content oil collecting pipeline is easy to form a 'gel plug' in the flowing process, so that the pressure of the test pipe section is increased, the gel plug is pushed out by liquid flow in the pipeline, the pipeline cleaning operation is similar to that of the pipeline, and after the pipeline is cleaned, the pressure drop of the test pipe section is reduced. Therefore, the pressure drop obtained by using the traditional loop experimental method often fluctuates drastically along with the time, and a relatively rich experimental experience is needed to be read to find the so-called initial temperature of "oil condensation and wall sticking". The cold finger method is also applied to research on the wall sticking rule of the oil condensate at present. However, conventional cold finger experimental apparatus often suffer from two drawbacks, (1) the inability to simulate actual pipe flow shear rates. (2) After the oil-water mixture is added into the cold finger at one time, the crude oil consumed by wall sticking cannot be supplemented. The cold finger inner flow field is different from the oil collecting pipeline and is inconsistent with the flow form of the actual pipe flow. The wall sticking condition of the local pipeline can only be reflected