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CN-121991656-A - Long-naked-hole dual-density curable plugging working solution and construction process thereof

CN121991656ACN 121991656 ACN121991656 ACN 121991656ACN-121991656-A

Abstract

The invention provides a long-naked-eye dual-density curable plugging working solution and a construction process thereof, wherein the low-density curable plugging working solution and the high-density curable plugging working solution are pumped in sequence, the volume ratio of the low-density curable plugging working solution to the high-density curable plugging working solution is 3:3-5, the density of the low-density curable plugging working solution is 1.25-1.35g/cm 3 , and the density of the high-density curable plugging working solution is 2.0-2.1g/cm 3 . The invention solves the technical difficulties of unreasonable low-density plug retention, easy leakage recovery, no plug retention at high density, low plugging success rate and the like of the traditional low-density curable plugging working solution and high-density curable plugging working solution. The low-density curable plugging working solution has a multistage cooperation effect, all materials are smaller than 1mm, but can plug a seam plate of 3mm, so that a precursor without sealing a door enters a leakage layer, the leakage layer is better sealed through a stacking-gelling-curing process, and the high-density curable plugging working solution provides higher liquid column pressure of a shaft.

Inventors

  • ZHU MINGMING
  • Hou Yakuo
  • SUN HUAN
  • NI HUAFENG
  • SHI CHONGDONG
  • YANG GUANG
  • ZHAO FURONG
  • WANG KAI
  • QU YANPING
  • ZHANG QIN

Assignees

  • 中国石油天然气集团有限公司
  • 中国石油集团川庆钻探工程有限公司

Dates

Publication Date
20260508
Application Date
20241107

Claims (10)

  1. 1. The long-naked-eye dual-density curable plugging working solution is characterized by comprising a low-density curable plugging working solution and a high-density curable plugging working solution which are pumped in sequence, wherein the volume ratio of the low-density curable plugging working solution to the high-density curable plugging working solution is 3:3-5, the density of the low-density curable plugging working solution is 1.25-1.35g/cm 3 , and the density of the high-density curable plugging working solution is 2.0-2.1g/cm 3 .
  2. 2. The long-bore hole dual-density curable plugging working fluid of claim 1, wherein the low-density curable plugging working fluid comprises water, and further comprises 50% of G-grade oil well cement, 35-40% of a lightening material, 1-2% of a retarder, 1-3% of a fluid loss agent, 3% of a flexible steel wire and 5-8% of a rigid material by mass percent of water.
  3. 3. The long-bore hole dual-density curable plugging working fluid of claim 1, wherein the high-density curable plugging working fluid comprises water, and further comprises 50% of G-grade oil well cement, 10-15% of weighting agent, 1-2% of retarder and 1-3% of fluid loss additive by mass percent.
  4. 4. The dual-density curable plugging working fluid with long naked eyes according to claim 2, wherein the lightening material is expanded perlite or hollow glass beads.
  5. 5. The long-naked-eye dual-density curable plugging working fluid according to claim 2, wherein the length-diameter ratio of the flexible steel wire is 100-90:1, and the length of the flexible steel wire is 10-9mm.
  6. 6. The long-naked-eye dual-density curable plugging working solution according to claim 2, wherein the rigid material is modified quartz sand with the particle size of 0.5-1mm, and the surface of the rigid material is treated by adopting 10 ten thousand molecular weight potassium polyacrylate to carry out spraying process.
  7. 7. The long-naked-eye dual-density curable plugging working solution according to claim 2 or 3, wherein the retarder is modified starch, and the fluid loss additive is polyvinyl alcohol.
  8. 8. The dual-density curable plugging working fluid with long naked eyes according to claim 3, wherein the weighting agent is iron ore powder, and the density of the weighting agent is 3.8-4.3g/cm 3 .
  9. 9. The construction process of the long-naked-eye dual-density curable plugging working solution according to any one of claims 1 to 8, which is characterized by comprising the following steps: Step 1), a plugging drilling tool is lowered to a leaking layer, then a shaft is washed for 5-10min, and the leaking layer is lifted to 100-150 m; step 2), pumping 10-15m 3 of low-density curable plugging working solution by adopting a drilling pump; Step 3) adopting a cementing cement truck tail pursue high density curable plugging working solution of 20-25m 3 ; step 4) taking out the drill pipe until the safe well section is reached, flushing the drill pipe 3-5 sides by using drilling fluid, and simultaneously calculating the length of the reserved plugging working fluid section in the well shaft; Step 5) if the length of the reserved plugging working fluid section in the shaft is less than 100m, directly taking out, and waiting for the gel to sweep the plug for 16-18h, and if the length of the reserved plugging working fluid section in the shaft is more than 100m, circulating the drilling fluid for 2-3 weeks, taking out, and waiting for the gel to sweep the plug for 16-18 h.
  10. 10. The construction process of the long-bore dual-density curable plugging working fluid according to claim 9, wherein the length l of the reserved plugging working fluid section in the shaft in the step 4) is calculated according to the following formula: l=(V-V 1 -V 2 )/S Wherein V 1 is the difference between the total amount of the normal pumping-in double-density curable plugging working fluid V and the return amount of the plugging working fluid after the plugging working fluid is discharged from the drilling tool, V 2 is the difference between the actual filling amount and the stress filling amount of the drilling fluid when the drilling tool is discharged, and S is the volume of a shaft.

Description

Long-naked-hole dual-density curable plugging working solution and construction process thereof Technical Field The invention belongs to the technical field of petroleum and natural gas deep coal gas drilling plugging, and particularly relates to a long-hole double-density curable plugging working fluid and a construction process thereof, which are suitable for plugging a long-hole large-shaft well leakage. Background The coal rock gas resources are abundant in China, and the coal rock gas is divided into shallow coal rock gas and deep coal rock gas according to the burial depth and the development technical difficulty, namely, the coal rock gas with the vertical depth within 2000m is the shallow coal rock gas, and the coal rock gas with the vertical depth above 2000m is the deep coal rock gas. The development of shallow coal and rock gas is mainly performed before 2021, but as the development technologies of deep coal and rock gas reservoir formation mechanism, exploration and development theory, large-scale fracturing and the like are gradually matured, the exploration of deep coal and rock gas is initially scaled, the eastern part of an Erdos basin is built into the largest deep coal and rock gas industrial area at present, and the exploration and development of a new layer system in the new field are developed, wherein the well structure design of phi 444.5mm drill bit multiplied by phi 339.7mm sleeve, phi 311.2mm drill bit multiplied by phi 244.5mm sleeve and phi 215.9mm drill bit multiplied by phi 139.7mm sleeve is adopted. The deep coal and rock gas of the Erdos basin is buried more than 2500m in depth, the higher drilling fluid density is required to maintain the stability of the well wall of the deep coal and rock along with the increase of drilling depth, but more than 10 complex layers need to be drilled before the deep coal and rock gas is drilled, multiple low-pressure-bearing and easy-leakage layers and crack layers exist in the same open hole well bore simultaneously, such as a Roche group (600-800 m) and an extension group (1200-1300 m), the juncture is poor, induced cracks are easy to occur, the Liu family ditch group (2000-2200 m) is cracked, the open hole is extremely easy to cause malignant leakage, the lower crack type Liu family ditch layer is easy to induce cracks in the plugging and squeezing process, secondary well leakage occurs in the upper pressure-bearing and weak layer Roche group, the two-open hole dimension phi 311.2mm is large, and the plugging difficulty is greatly increased. How to realize high-efficiency safe plugging of a plurality of easy-to-leak layers of a long-hole large-bore well bore under the same-existence condition is a technical problem to be solved in the field of well drilling plugging at present, and various curable plugging slurry systems including low-density cement, multistage cement, delay expansion plugging working fluid and the like are invented at present. Patent publication No. CN106281265A discloses an ultralow density plugging agent suitable for low-pressure easy-to-leak stratum and a preparation method thereof. The plugging agent is prepared from water, gel plugging agent, plugging fiber, surfactant, light rigid plugging additive, polymer and water-absorbing expansion resin, wherein the continuous phase is water, the added gel plugging agent accounts for 50-70% of the mass of the ultra-low density plugging slurry, the mass of the plugging fiber is 0.1-0.3%, the mass of the surfactant is 2.5-3.5%, the mass of the light rigid plugging additive is 2-6%, the mass of the polymer is 1-2%, the mass of the water-absorbing expansion resin is 0.5-2%, the density of the plugging agent prepared by the invention can reach 1.0g/cm < 3 > at the minimum through internal test, the density is adjustable, the plugging agent has good temperature resistance, the temperature resistance can reach 180 ℃, the plugging agent is particularly suitable for plugging deep wells, the plugging of ultra-deep wells, the pressure bearing capacity is more than or equal to 15MPa, the plugging depth is large, and the plugging agent has the characteristics of good effect, and can plug large-size cracks, pores, cracks and other various types of stratum leaks. The patent with the publication number of CN117945692A discloses a multistage particle-matched low-density well cementation material, which consists of a low-density micro-silicon nano-scale material, hollow vitrified micro bubbles, a stabilizing material and a reinforcing agent, wherein the mass ratio of the low-density micro-silicon nano-scale material to the high-performance hollow vitrified micro bubbles to the stabilizing material to the reinforcing agent is 6:4:1-2:2-3. The low-density cement slurry system prepared by the invention has low equivalent density which can reach 1.20-1.25g/cm 3 at the minimum, has a certain stabilizing effect under high temperature and high pressure conditions, has rapid development of cement stone