I. Status Quo of Sealing and Blocking Water Leakage Technology
Selectable plugging agent: oil well cement, composite water plugging agent (cement as the main body)
Question:
1.Low strength and easy to fail: Solid plugging agents have a certain particle size and concentration, making it difficult to enter pores and deep parts of the formation, and can only achieve surface plugging in the form of filter cake.
2. The sealing parts are not resistant to acid and alkali, making it difficult and expensive to implement post-stimulation measures.The sealing medium is cement, clay, calcium mineral powder, and other acid-resistant materials, requiring tool protection during post-stimulation acidification.
3. Construction risks are high.High solid content is prone to deposition, flash condensation, and rapid fluid loss, resulting in flagpole or enema accidents.
4. It is highly destructive to the casing.The pressure during squeeze injection is high, ranging from 25 to 30 MPa, which is destructive to the casing and not suitable for some wells.
The blocking agent for blocking bottom water can be selected from polymer gel, oil well cement
Question:
1. There is no relatively mature plugging agent available.The strength of cross-linked gel is low，There are many influencing factors, and the gelation property is poor.The polymer degrades quickly, usually within 6-24 months.It is impossible to achieve blasthole plugging.It is rarely used in water plugging applications.
2. Cement-based solid phase plugging agents cannot enter the mid-deep part and cannot meet the requirements for diaphragm installation.
3. Seamless connection between medium-deep plugging and blasthole plugging cannot be achieved, and the junction between the two systems is prone to forming an overflow channel.
Ⅱ、 Compound modified resin blocking agent
1. The curing time control of compound modified resin plugging agent is a key index to determine its practicality and application range, and the curing time must meet the safe construction under different temperatures. By adding slow
The slow release technology gradually increases the concentration of curing agent in the system to control the curing time
Of the.
2. Thickening of the system can enhance the ability to suspend solids and improve the coverage of plugging agent,
Effectively reduce the fingering degree of plugging agent and promote the uniform advancement of plugging agent in the target layer.
3. Solid-phase filling technology can be greatly improved through solid phase bridging and liquid-phase filling coordination
Longitudinal filling degree of plugging agent and sealing strength of near-well zone improve the success rate of one-time plugging.
Performance Comparison of Compound Modified Resin Sealing Agent
Ⅲ、 Key technical points:
1. Development of delayed curing agent, strong regulation of curing time (0.5 hour - 15 days), wide temperature range (20-150 ℃).
2. The system thickening technology can make the viscosity of the system adjustable within the range of 17-2000mPa. s. The sweep filling rate of the plugging agent and the suspension capacity of the solid phase filler are greatly improved, and the plugging capacity is significantly enhanced.
3. The research on filling material solves the problem of effective wall building after resin consolidation and realizes effective sealing of high permeability stratum.
The development of this technology makes it possible to evaluate the performance of compound modified resin plugging agent for the smooth implementation of difficult measures such as horizontal section plugging, secondary cementing for wells with difficult circulation and acidizing without moving the string after plugging
4、 Performance evaluation of compound modified resin plugging agent:
It can meet the technical requirements of different curing time at different temperatures of 20-150 ℃, curing time at different temperatures and breakthrough pressure.
2. The viscosity of the system can be adjusted at 20-10000mPa. s.
The high viscosity greatly improves the comprehensive performance of the system, and key technical indicators such as suspension, uniform injection and consolidation body stability are greatly enhanced.
3. The addition of filler greatly improves the plugging performance of plugging agent.
Select filling materials with different particle sizes and fully mix them according to a certain proportion.
Sand filling pipe with diameter of 2.54cm and length of 30cm shall be filled with 16-20 mesh quartz sand wet method, and plugging agent with different ratio shall be injected.
Observe the change of displacement pressure and volume of outlet produced fluid with the injection of plugging agent to evaluate the plugging capacity of plugging agent system mixed with filling materials.
The resin base fluid basically has no pressure display during the injection of high permeability sand filling pipe, but the pressure rises rapidly with the injection of plugging agent after mixing with the filling material, and the outlet filtration is small. The experimental results show that the plugging capacity of high concentration is stronger than that of low concentration, and the filtration loss is smaller; The plugging capacity of large particle size (400 meshes) is stronger than that of small particle size (800 meshes), and the filtration loss is small.
4. The core plugging capacity is greatly enhanced, the plugging rate is more than 99%, and the breakthrough force is>25MPa.
Ⅴ、 Field test condition
Feature 1: High success rate of field implementation.
Feature 2: It is suitable for process, with small construction risk, and can realize effective plugging of cased wells of different types and specifications.
Feature 3：Low squeezing pressure plugging, beneficial to casing protection
Feature 4: One-time sealing of thick and multi-layer layers
Feature 5: It can be used for plugging lost wells with well temperature of 65 － 100 ℃
Feature 6: Small density of drilling cuttings, easy return and fast plug
7、 Type and effect of field implementation measures
Measure type I: obvious water plugging effect of bottom water reservoir.
Example: Well 32-X3214
Basic information:
This well is a development well in Block 3-2, designed for rolling development of Ng oil reservoir and taking into account the distribution of oil layers in Nm. As Layer 32 # is the bottom water reservoir, in order to prevent water channeling after production, the research determines to remove the plug at the oil-water interface of Layer 32 #, the target formation for oil testing
Perforation process
Implementation status
The test plug surface is 2698.36m after waiting for setting for 48h, with reserved plug of 175m (replacement of reserved plug of 100m during construction). The pressure test for the plugging section after drilling plug is 25MPa, which is qualified
Measure type 1: apparent water plugging effect of bottom water reservoir
The well has been without water production since early plugging, with a maximum daily output of 60 tons of crude oil. At present, the production is controlled, with a daily output of 30 tons. Up to now, the cumulative output of crude oil is 2684 tons.
Measure type II. Obvious sealing effect of channeling sealing well
It has been producing with low water cut (<4%) after normal well opening, with daily oil output of 15t. So far, 520t crude oil has been produced.
Construction effect of early water plugging
Measure type III: horizontal well sealing wellbore
Pressure test of 25MPa after waiting for 48 hours is qualified; CP5 had serious leakage before plugging. Through temporary plugging and post-plugging screen pipe process, the placement and effective retention of plugging agent in the wellbore and around the well were ensured. The common plugging agent is about 30 m3.
Conclusion:
Composite modified resin plugging agent breaks through the problem of perforation plugging through technical support. It has the dual advantages of fluid chemical plugging agent and strong sealing capacity plugging agent, and realizes the seamless connection of a system of middle-deep water plugging and near-well and blasthole plugging.
It can be widely used for sealing (unprotected acidizing can be implemented), circulation of secondary cementing, deep water plugging (bottom water plugging, water plugging in the formation), channel sealing, casing change well water plugging and other measures.
application prospect
1. The sealing layer construction of high aquifer can meet the acid stimulation without moving the string in the later period.
2. It can be used for the secondary fixation of casing, with good mobility of composite modified resin, adjustable curing time, small construction risk, and construction with tools; It can be used for plugging the channeling outside the pipe with corresponding tools.
3. Selective squeezing and sealing of partial multi-layer commingling well
