Method of cement for well cementing in penetrated hydrate layer

Patent metadata

Field	Value
Publication number	US-11719658-B2
Application number	US-202217994420-A
Country	US
Kind code	B2
Filing date	Nov 28, 2022
Priority date	Jan 21, 2021
Publication date	Aug 8, 2023
Grant date	Aug 8, 2023

Abstract

A performance evaluation device and a design method of a cement for well cementing in a penetrated hydrate layer are provided. The performance evaluation device includes an equivalent wellbore, an inner circulation system, an outer circulation system, a thermal insulation cover, a bracket, a temperature sensing system, and a cement mold. The device can simulate a true downhole situation, conduct an evaluation experiment on the heat insulation performance of a cementing cement, and conduct experiments at different temperatures with automatic temperature control. The design method is to use a low-hydration, early-strength, and heat-insulating cement slurry system during the well cementing in a penetrated hydrate layer, where the low-hydration and early-strength characteristics ensure the effective sealing of a hydrate layer during a cementing process, and the heat insulation characteristic results in low heat conductivity and thus can ensure the stability of a hydrate layer during a production operation.

First claim

What is claimed is:

1. A design method of a cement for well cementing in a penetrated hydrate layer, wherein a low-hydration, early-strength, and heat-insulating cement slurry system is used during the well cementing in the penetrated hydrate later, and the penetrated hydrate layer is a hydrate layer penetrated by a casing pipe, comprising the following steps:
(1) collecting a formation sample of a cementing-target penetrated hydrate layer, testing physical parameters of the formation sample, and acquiring environmental parameters of the cementing-target penetrated hydrate layer;
(2) analyzing the physical parameters of the formation sample, and determining early strength performance requirements, hydration heat performance requirements, and heat insulation performance requirements of a cement slurry meeting cementing conditions based on field operation requirements;
(3) according to the early strength performance requirements of the cement slurry, testing effects of various early-strength agents, and selecting an early-strength agent with optimal performance from the various early-strength agents;
(4) according to the hydration heat performance requirements of the cement slurry, testing effects of various low-hydration-heat materials, and selecting a low-hydration-heat material with optimal performance from the various low-hydration-heat materials;
(5) according to the heat insulation performance requirements of the cement slurry, testing effects of various heat-insulating materials, and selecting a heat-insulating material with optimal performance from the various heat-insulating materials;
(6) preparing the early-strength agent with the optimal performance, the low-hydration-heat material with the optimal performance, the heat-insulating material with the optimal performance and the cement slurry into the low-hydration, early-strength, and heat-insulating cement slurry system to adjust performance of the cement slurry, such that the cement slurry has low hydration, early strength, and heat insulation performance and meets requirements of a cementing construction;
(7) using a performance evaluation device of a cement for well cementing in a penetrated hydrate layer to simulate a cementing process of the penetrated hydrate layer, and determining whether performance of the low-hydration, early-strength, and heat-insulating cement slurry system meets the requirements of the cementing construction; and if the requirements of the cementing construction are met, proceeding to step (8), and if the requirements of the cementing construction are not met, repeating steps (3) to (6); and
(8) estimating a cement slurry injection volume required by the cementing-target penetrated hydrate layer, and injecting the low-hydration, early-strength, and heat-insulating cement slurry system meeting the requirements of the cementing construction into the formation sample in a form of a displacement liquid according to field operation conditions and corresponding construction parameters until the cement slurry reaches a predetermined solidification range.

2. The design method of the cement for well cementing in the penetrated hydrate layer according to claim 1 , wherein the physical parameters of the formation sample comprise a formation temperature, a formation pressure, and a hydrate saturation.

3. The design method of the cement for well cementing in the penetrated hydrate layer according to claim 1 , wherein the cement slurry has consistency of less than 70 Bearden before the low-hydration, early-strength, and heat-insulating cement slurry system is completely pumped into the formation sample; a pumping time of the low-hydration, early-strength, and heat-insulating cement slurry system is controlled within 1 hour to 2 hours; and a compressive strength of the low-hydration, early-strength, and heat-insulating cement slurry system is no less than 3.5 MPa within 24 hours at 20° C.

4. The design method of the cement for well cementing in the penetrated hydrate layer according to claim 1 , wherein the heat-insulating material with the optimal performance comprises a hollow glass microsphere, obturator perlite, or a vitrified micro bubble.

5. The design method of the cement for well cementing in the penetrated hydrate layer according to claim 1 , wherein the determining whether the performance of the low-hydration, early-strength, and heat-insulating cement slurry system meets the requirements of the cementing construction in step (7) comprises the following specific steps:
S1: placing an equivalent wellbore into a placement cavity inside an outer cavity body, and adding an equivalent fluid to an annular cavity of the equivalent wellbore;
S2: hoisting an inner cavity body into a through-cavity of the equivalent wellbore, and lowering the inner cavity body until a capped edge at an upper end of the inner cavity body is clamped at an upper end of the equivalent wellbore; and allowing a high-temperature thermostatic bath to communicate with an inner circulation cavity through an inner circulation pipeline to form an inner circulation system;
S3: adding sand and mud into the placement cavity inside the outer cavity body to form an annular sand and mud layer, compacting the annular sand and mud layer, and reserving an annular space between the annular sand and mud layer and an outer wall of the equivalent wellbore;
S4: slowly pouring the cement slurry into the annular space between the annular sand and mud layer and the outer wall of the equivalent wellbore; and when the cement slurry is slightly solidified, inserting metal shells of a first group of temperature sensors into the cement slurry at equal intervals in a radial direction, and inserting metal shells of a second group of temperature sensors into the annular sand and mud layer at equal intervals in the radial direction, wherein the metal shells are inserted at a depth to allow a bottom end of each of the metal shells to be located in a middle of the cement slurry and the annular sand and mud layer;
S5: after the cement slurry is completely solidified, inserting probes of the first group of temperature sensors and probes of the second group of temperature sensors into the metal shells sequentially, and connecting the probes to a temperature measuring instrument;
S6: allowing a low-temperature thermostatic bath to communicate with an outer circulation cavity through an outer circulation pipeline to form an outer circulation system, opening the low-temperature thermostatic bath and covering a thermal insulation cover to cool an entire device, and starting an experiment after a temperature of the entire device is stable;
S7: opening the high-temperature thermostatic bath to heat the inner cavity body, recording a temperature change curve of each of the first group of temperature sensors and the second group of temperature sensors, and closing the high-temperature thermostatic bath and the low-temperature thermostatic bath when the temperature of the entire device remains unchanged; and
S8: comparing an experimental result with a performance index, and determining a heat insulation performance rate of the cement slurry used in the experiment to evaluate performance of the cement slurry.

6. The design method of the cement for well cementing in the penetrated hydrate layer according to claim 5 , wherein a preparation method of the cement slurry in S4 comprises: according to a required cement sheath cementing experiment, weighing various solid materials by an electronic scale based on a cement slurry formula given on site, pouring the various solid materials into a bucket, and thoroughly stirring the various solid materials with a long stirring rod; and pouring the various solid materials into a liquid material, and using a stirrer to stir at a medium speed for 3 min to 5 mi

Assignees

• Univ China Petroleum East China

Inventors

• Bu Yuhuan
• Shen Shengda
• Lu Chang
• Liu Huajie
• Guo Shenglai
• Shan Xun
• Ma Rui

Classifications

• G01N25/18 Primary

  by investigating thermal conductivity (by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18) · CPC title

• E21B33/14

  for cementing casings into boreholes · CPC title

• E21B49/02

  by mechanically taking samples of the soil · CPC title

• G01N33/383

  Concrete or cement · CPC title

• E21B47/005

  Monitoring or checking of cementation quality or level · CPC title