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Cross-linked plugging agent stimulated by high density brine and preparing method thereof

a plugging agent and high density brine technology, applied in the field of oilfield chemistry, can solve the problems of increasing the cost, increasing the requirement, and high cost during well completion and workover, and achieves the effects of good pumpability, effective protection of the reservoir, and viscosity of the plugging agen

Inactive Publication Date: 2021-04-15
SOUTHWEST PETROLEUM UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patent describes a cross-linked plugging agent that is stimulated by high density brine and can be used in high-temperature, high-pressure oil and gas environments. The plugging agent can be easily prepared on site and is stable at high temperatures and densities. It can withstand corrosion, is degraded controllably, and is environmentally friendly. The plugging agent is also cost-competitive and has good viscosity and pumpability. This patent offers a new and efficient solution for well completion, workover, and protection of oil and gas reservoirs.

Problems solved by technology

Many challenges and difficulties need to be dealt with such as high temperature, high pressure, multi-pressure environment in reservoir, blowout and fluid loss.
In case of drilling a well with ultra high pressure, the contradiction of well killing and fluid loss in low-pressure reservoir is the main technical difficulty which results in high cost during well completion and workover.
The fluid loss results in more requirements of killing fluid to keep the pressure, which increases the cost.
In serious condition, the fluid loss damages the reservoir and reduces the outcome.
In an even more serious condition, the fluid loss induces safety risk.
Haloid especially bromide solution is highly corrosive under high temperature and high density environment and difficult to degrade, which accumulates in food chain and is not environmentally friendly.
The application of this type of plugging agent is limited and this type of plugging agent is not able to be used under high pressure difference.
If the size of the granule is not selected carefully, the granules easily enter the reservoir and damage the reservoir.
Although the plugging agent prepared based on formate has the advantages of wide density range and effectively protecting the reservoir, the price of the formate especially cesium formate is much higher than halide salt, which restrict the use of the plugging agent.

Method used

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  • Cross-linked plugging agent stimulated by high density brine and preparing method thereof
  • Cross-linked plugging agent stimulated by high density brine and preparing method thereof
  • Cross-linked plugging agent stimulated by high density brine and preparing method thereof

Examples

Experimental program
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Effect test

embodiment 1

[0042]A cross-linked plugging agent stimulated by high density brine for temporary blockage comprises the mixture of main agent of 70 wt %, gelling agent of 5 wt %-8 wt % and pure water. The experiment temperature is 120° C. The gelation time and a gelation strength are shown in the below table 2.

TABLE 2gelation time and a gelation strength in embodiment 1Gelling agentAging time / gel strength codecontent Wt %Initial2 h4 h12 h1 D3 D5 D7 D9 D12 D5ADGGGGGGGG7ADGGGGGGGG8ADGGGGGGGG

[0043]As shown in Table 2, the gelation time is within 2-4 hours; the final forming strength is G; no syneresis happens within 12 days.

[0044]As shown in FIG. 1, the values of elastic modulus and loss modulus of various gelling agent content after aging for three days prove that the strength of the plugging agent is able to be adjusted by adjusting the gelling agent content.

embodiment 2

[0045]A cross-linked plugging agent stimulated by high density brine for protection of reservoir near perforations comprises main agent of 70 wt %, gelling agent of 1.5 wt %-3 wt % and pure water. The experiment temperature is 160° C. The gelation time and a gelation strength are shown in the below Table 3.

TABLE 3gelation time and a gelation strength in embodiment 2Gelling agentAging time / gel strength codecontent Wt %Initial4 h8 h1 D2 D3 D4 D1.5ABDDDDAsyneresis2ABDDDDDsyneresis2.5ABEEEEEsyneresis3ABEEEEE

[0046]As shown in table 3, the gelation time is within 4-8 hours; the final forming strength is D or E; syneresis and degradation occur on the third day; the plugging agent degrades to solid-free and low viscosity fluid 48 hours after syneresis begins.

[0047]As shown in FIG. 2, the viscosity and shear force curve of the plugging agent with 2 wt % of gelling agent content at the initial time, after two days and after five days illustrates the viscosity of the plugging agent at the init...

embodiment 3

[0048]A cross-linked plugging agent stimulated by high density brine for temporary blockage comprises main agent of 70 wt %, gelling agent of 6 wt %-8 wt % and pure water. The experiment temperature is 90° C. The gelation time and a gelation strength are shown in the below table 4.

TABLE 4gelation time and a gelation strength in embodiment 3Gelling agentAging time / gel strength codecontent Wt %Initial2 h4 h12 h1 D3 D5 D7 D9 D12 D6ADFFFFFFFF7ADFGGGGGGG8ADGHHHHHHH

[0049]As shown in table 4, the gelation time is within 2-4 hours; the final forming strength is F, G or H; no syneresis happens within 7 days. The plugging agent is able to be applied in temporary blockage and water plugging when different gel strength is required.

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Abstract

The present invention disclosed a cross-linked plugging agent stimulated by high density brine which comprises main agent: 10 wt %-90 wt %, gelling agent: 0.5 wt %-9 wt % and pure water; wherein the main agent is selected from the group consisting of a Dipotassium phosphate (K2HPO4), a Tripotassium phosphate (K3PO4) and a Potassium pyrophosphate (K4P2O7), a Potassium Dihydrogen Phosphate (KH2PO4), a Sodium dihydrogen phosphate (NaH2PO4); the gelling agent is selected from the group consisting of a Xanthan gum and a kappa carrageenan. The gelling time is controlled within 0.5-12 h under an experiment temperature of 90° C.-160° C. The final gelling strength is controlled within D-H. The density is controlled within 1.0-1.55 g / cm3. The plugging agent is able to be applied in well completion and workover under high temperature, high pressure, multi-pressure series of strata oil and gas environment when temporary blockage and leak proof is required, protection of reservoir near perforations and water plugging.

Description

CROSS REFERENCE OF RELATED APPLICATION[0001]This is a Continuation Application of the International Application PCT / CN2020 / 076004, filed Feb. 2, 2020, which claims priority under 35 U.S.C. 119(a-d) to CN 202010094980.1, filed Feb. 17, 2020.BACKGROUND OF THE PRESENT INVENTIONField of Invention[0002]The present invention relates to oilfield chemistry, which is widely applied in well completion and workover under high temperature, high pressure, multi-pressure oil and gas environment and is applied in temporary blocking agent, perforating protect fluid and water shutoff agent. The present invention is more particularly related to the cross-linked plugging agent stimulated by high density brine and the preparing method thereof.Description of Related Arts[0003]The reservoir development goes deeper and deeper to reach deep and ultra-deep formation where the geological condition is complicate and prone to change. Many challenges and difficulties need to be dealt with such as high temperatu...

Claims

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Application Information

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IPC IPC(8): C09K8/42C09K8/44E21B33/13
CPCC09K8/426E21B33/13C09K8/44C04B28/344C04B22/0026C04B24/38C09K8/512C09K8/516
Inventor JIA, HUDAI, SHANGKUN
Owner SOUTHWEST PETROLEUM UNIV
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