CN-121991654-A - Method for adjusting density of recyclable foam drilling fluid

CN121991654ACN 121991654 ACN121991654 ACN 121991654ACN-121991654-A

Abstract

The invention relates to the technical field of foam drilling, in particular to a method for adjusting the density of recyclable foam drilling fluid, which comprises the steps of adding a foaming agent into water for circulation to obtain a recyclable foam drilling fluid system in an ultralow density state; adding a foaming agent and a foam stabilizer into water for circulation to obtain a low-density recyclable foam drilling fluid system, adding the foaming agent, the foam stabilizer and a viscosity increaser into the water for circulation to obtain a medium-density recyclable foam drilling fluid system, and adding the foaming agent, the foam stabilizer, the viscosity increaser and inorganic salt into the water for circulation to obtain a high-density recyclable foam drilling fluid system. According to the current density of the recyclable foam drilling fluid, the density of the recyclable foam drilling fluid is adjusted by adding inorganic salt or a stabilizer and a foaming agent to achieve the target density, so that the density adjustment of the recyclable foam drilling fluid system is realized, meanwhile, a recyclable foam structure which can adapt to different water-containing environments is formed by utilizing the actions of intermolecular forces, hydrophobic association forces and the like, and the novel recyclable foam drilling fluid has high efficiency, flexibility and extremely wide adaptability.

Inventors

QIAO DONGYU
SHANG KAIKAI
WANG XUECHENG
LIU LING
ZHANG XINWEN
WANG JUN
CHEN JIE
GUO XU
TANG YUKE
YU JIANG

Assignees

中国石油天然气集团有限公司
中国石油集团西部钻探工程有限公司

Dates

Publication Date: 20260508
Application Date: 20241105

Claims (10)

1. A method of adjusting the density of a recyclable foam drilling fluid, comprising: Preparing a recyclable foam drilling fluid system in an ultralow density state; Preparing a low-density recyclable foam drilling fluid system; preparing a medium-density recyclable foam drilling fluid system; A high density state recyclable foam drilling fluid system is formulated.
2. The method of adjusting the density of a recyclable foam drilling fluid as defined in claim 1, wherein the specific process of formulating the ultra low density state recyclable foam drilling fluid system comprises: And adding 0.1 to 0.3 percent of foaming agent into water according to the mass percent, and circulating for 1 to 2 weeks at the displacement of 450 to 550L/min to obtain the ultra-low density state recyclable foam drilling fluid system.
3. The method of adjusting the density of a recyclable foam drilling fluid according to claim 1 or 2, wherein the specific process of formulating the low density state recyclable foam drilling fluid system comprises: adding 0.1 to 0.3 percent of foaming agent and 0.1 to 0.3 percent of foam stabilizer into water according to mass percent, and circulating for 1 to 2 weeks at a displacement of 450 to 550L/min to obtain the low-density recyclable foam drilling fluid system.
4. A method of adjusting the density of a recyclable foam drilling fluid as defined in claim 1, claim 2 or claim 3, wherein the specific process of formulating the medium density state recyclable foam drilling fluid system comprises: According to the mass percentage, 0.1 to 0.3 percent of foaming agent, 0.1 to 0.3 percent of foam stabilizer and 0.4 to 0.8 percent of adhesion promoter are added into water, and the mixture is circulated for 1 to 2 weeks at a discharge rate of 450 to 550L/min to prepare the medium-density recyclable foam drilling fluid system.
5. The method of adjusting the density of a recyclable foam drilling fluid as described in any one of claims 1 to 4, wherein the specific process of formulating the high density state recyclable foam drilling fluid system comprises: Adding 0.1 to 0.3 percent of foaming agent, 0.1 to 0.3 percent of foam stabilizer, 0.4 to 0.8 percent of adhesion promoter and 1 to 20 percent of inorganic salt into water according to mass percent, and circulating for 1 to 2 weeks at a displacement of 450 to 550L/min to prepare the high-density recyclable foam drilling fluid system.
6. The method of adjusting the density of a recyclable foam drilling fluid according to any one of claims 1 to 5, characterized by distinguishing according to a recyclable foam drilling fluid system target density value, comprising: The recyclable foam drilling fluid system is in an ultralow density state when the target density value of the recyclable foam drilling fluid system is less than or equal to 0.10g/cm 3 and is less than or equal to 0.40g/cm 3 ; The recyclable foam drilling fluid system is in a low density state when the target density value of the recyclable foam drilling fluid system is less than or equal to 0.40g/cm 3 and less than or equal to 0.80g/cm 3 ; The recyclable foam drilling fluid system is in a medium density state when the target density value of the recyclable foam drilling fluid system is less than or equal to 0.80g/cm 3 and less than or equal to 0.95g/cm 3 ; the recyclable foam drilling fluid system is in a high density state when the target density value of the recyclable foam drilling fluid system is not more than 0.95g/cm 3 and not more than 1.20g/cm 3 .
7. The method for adjusting the density of the recyclable foam drilling fluid according to claim 6, wherein when the density value of the obtained recyclable foam drilling fluid system exceeds the target density value of the recyclable foam drilling fluid system when the recyclable foam drilling fluid system in a medium density state and the recyclable foam drilling fluid system in a high density state are prepared, the mass ratio of the foaming agent, the foam stabilizer and the adhesion promoter is adjusted to be 1:1:3, wherein the foaming agent, the foam stabilizer and the adhesion promoter are respectively added for a plurality of times according to the mass percentage of 0.1%, and the recyclable foam drilling fluid system density value is detected after stirring for 10min at a speed of more than 10r/min after single addition until the recyclable foam drilling fluid system density value is reduced to the target density value of the recyclable foam drilling fluid system.
8. The method for adjusting the density of a recyclable foam drilling fluid according to any one of claims 5 to 7, wherein the mass of the added inorganic salt when preparing the recyclable foam drilling fluid system in a high density state is calculated as follows: Wherein W is the mass of the added inorganic salt, kg, V 1 is the volume of the current recyclable foam drilling fluid system, m 3 ;ρ 1 is the density value of the inorganic salt, kg/m 3 ;ρ 2 is the density value of the current recyclable foam drilling fluid system, kg/m 3 ;ρ 3 is the target density value of the system, and kg/m 3 .
9. The method of adjusting the density of a recyclable foam drilling fluid as described in any one of claims 5 to 8, wherein the foaming agent comprises betaine and ethylene glycol, or/and the foam stabilizer comprises polyanionic cellulose and carboxymethyl cellulose, or/and the viscosity enhancer comprises xanthan gum and sodium metaaluminate, or/and the inorganic salt is potassium formate.
10. The method of adjusting the density of a recyclable foam drilling fluid as set forth in claim 9, wherein the mass ratio of betaine, glycol, polyanionic cellulose, carboxymethyl cellulose, xanthan gum, sodium metaaluminate is from 0.2 to 1:0.2 to 1:5 to 10:5 to 10:3 to 9:1 to 2.

Description

Method for adjusting density of recyclable foam drilling fluid Technical Field The invention relates to the technical field of foam drilling, in particular to a method for adjusting the density of recyclable foam drilling fluid. Background Currently, natural cracks are commonly developed in the stratum above the diving surface (400 m to 600m in vertical depth) of the chadado basin. In the process of drilling and completing, when the density of drilling fluid is too high and the pressure of a fluid column is high, a large pressure difference is formed between wellbore fluid and stratum, so that leakage is caused. Because the stratum above the submergence surface is generally loose and has weak mechanical strength, crack expansion is easily caused by disturbance of circulating pump pressure and tripping pressure, leakage is further aggravated, and the water loss of a single well can exceed 1000m 3. From the aspect of field application measures, the density of plugging materials such as conventional bridge plugs, cement paste and the like cannot be reduced, the density of various systems is generally more than 1.0g/cm 3, even 1.85g/cm 3, and the leakage pressure difference is large when the upper part of the diving surface drills. Therefore, the introduction of a low-density drilling fluid system is an important way for solving the problem of leakage of stratum above the diving surface of the Qida basin. The existing low-density drilling fluid system is represented by a foam system used by an air drill, but the system has unstable performance after foaming, particularly has low viscosity, cannot meet the requirement of carrying rock, has poor stability after meeting water, quickly breaks down the foam after drilling into shallow water yielding stratum, and cannot meet the drilling requirement of the upper part of the diving surface as a whole. For this reason, there is an urgent need for a recyclable foam system having a large adjustable density range (0.10 g/cm 3 to 1.20g/cm 3), sufficient viscosity, and stable in water. However, in the field construction, the volume of the ground drilling fluid preparation tank, the preparation stirring speed and the performance of the slurry preparation water are greatly different, and the method is limited by engineering practical and cost consideration, so that a unified and standard drilling fluid preparation environment is difficult to establish. At this time, the density of the prepared recyclable foam drilling fluid in different areas and under different working conditions on the site has larger deviation, and a targeted adjustment measure needs to be established by an introduction means. Disclosure of Invention The invention provides a method for adjusting the density of a recyclable foam drilling fluid, which overcomes the defects of the prior art, and can effectively solve the problems that the viscosity is low, the requirement of carrying rock cannot be met, the stability is poor after water is met, the foam is quickly broken after the foam is drilled into a shallow water outlet stratum, and the requirement of drilling on the upper part of a diving surface cannot be met in the use of the conventional low-density drilling fluid system. The technical scheme of the invention is realized by the following measures that the method for adjusting the density of the recyclable foam drilling fluid comprises the following steps: Preparing a recyclable foam drilling fluid system in an ultralow density state; Preparing a low-density recyclable foam drilling fluid system; preparing a medium-density recyclable foam drilling fluid system; A high density state recyclable foam drilling fluid system is formulated. The following are further optimizations and/or improvements to the above-described inventive solution: the specific process for preparing the ultra-low density state recyclable foam drilling fluid system comprises the following steps: And adding 0.1 to 0.3 percent of foaming agent into water according to the mass percent, and circulating for 1 to 2 weeks at the displacement of 450 to 550L/min to obtain the ultra-low density state recyclable foam drilling fluid system. The specific process for preparing the recyclable foam drilling fluid system in the low density state comprises the following steps: adding 0.1 to 0.3 percent of foaming agent and 0.1 to 0.3 percent of foam stabilizer into water according to mass percent, and circulating for 1 to 2 weeks at a displacement of 450 to 550L/min to obtain the low-density recyclable foam drilling fluid system. The specific process for preparing the medium-density state recyclable foam drilling fluid system comprises the following steps: According to the mass percentage, 0.1 to 0.3 percent of foaming agent, 0.1 to 0.3 percent of foam stabilizer and 0.4 to 0.8 percent of adhesion promoter are added into water, and the mixture is circulated for 1 to 2 weeks at a discharge rate of 450 to 550L/min to prepare the medium-density recyclabl