CN1624293A - Balanced Squeeze Injection Water Shutoff Technology with Natural Diversion - Google Patents

Abstract

The squeezing and pouring process for blocking bottom water and protecting oil-gas layer with non-selective blocking agent. The KH ratio of a reservoir to be blocked and a reservoir to be protected is comprehensively determined by utilizing data such as well logging, a liquid production profile and the like, the injection speed ratio of two fluids is determined according to the viscosity of a blocking agent and the viscosity of a fluid compatible with a stratum, a pipe column is lowered into the top of the stratum to be blocked before squeeze construction, the blocking agent is injected from the pipe column according to the determined injection speed ratio of the two fluids, the fluid compatible with the stratum is injected from an annulus, the blocking agent is injected into the stratum at a well section below the pipe column and at the lower part of the annulus, the liquid level of the two fluids in the annulus is naturally formed according to the physical properties of the reservoir and the injection speed of the two fluids, the two fluid interfaces are higher when the reservoir is higher for a homogeneous reservoir of carbonate rock, and conversely, the two fluid interfaces are lower when.

Description

Balanced Squeeze Injection Water Shutoff Technology with Natural Diversion

technical field

The invention relates to a deep water plugging and squeezing process for oil and gas wells, in particular to a non-selective plugging agent for plugging bottom water and protecting oil and gas reservoirs.

Background technique

At present, the known deep water plugging squeeze technology mainly includes general squeeze, packer layered squeeze, packer split flow squeeze, and γ-ray monitoring synchronous flow squeeze technology. The general squeeze technology requires that the plugging layer permeability ratio The oil layer is much higher or the plugging agent has obvious selectivity, and the stability of the selective plugging agent in high temperature formation is difficult to guarantee; the layered squeeze of the packer requires the formation to be layered; A packer is run between the plugged well section and the reserved well section, and the plugging agent is squeezed into the lower formation through the squeeze pipe string, and at the same time, the fluid compatible with the formation is squeezed into the annulus to achieve the purpose of protecting the oil layer. It is required to run a packer. It is risky to run a packer in open hole and perforated well sections. For homogeneous reservoirs such as carbonate rocks, the distribution of the reservoir is complicated, and the position of the packer may be inappropriate. As a result, one of the fluids cannot be squeezed in, and the purpose of construction cannot be achieved; the gamma-ray monitoring synchronous flow squeeze injection process does not add a packer, and squeezes the plugging agent into the lower formation through the squeeze string, and squeezes into the annulus at the same time. For the γ-ray-containing fluid compatible with the formation, the interface between the blocking agent in the annular space and the γ-ray-containing fluid compatible with the formation is monitored by monitoring the γ-ray intensity, and the synchronous flow extrusion is realized by adjusting the extrusion speed of the cement truck. It is complicated, and the plugging layer selected for the homogeneous carbonate reservoir is not necessarily reasonable, and it may also cause one of the fluids to be unable to squeeze in, failing to achieve the purpose of construction.

Contents of the invention

In order to overcome the deficiencies of the current deep water plugging technology, the present invention designs a balanced plugging water technology of natural diversion that realizes synchronous flow squeeze injection in open hole and perforated well sections, and at the same time reduces the complexity of construction.

The technical solution adopted by the present invention to solve the technical problem is: to comprehensively determine the KH ratio of the plugging reservoir and the protection reservoir by using data such as well logging and liquid production profile, and then determine according to the viscosity of the plugging agent and the fluid compatible with the formation The injection rate ratio of the two fluids. Before the squeeze construction, the pipe string is lowered to obviously exceed the top of the formation to be blocked, and the plugging agent is injected from the pipe string according to the injection speed ratio of the two fluids determined above. The fluid is injected from the annulus. Since the pipe string is obviously lowered than the top of the formation to be plugged, the plugging agent is injected into the formation from the well section below the pipe string and the lower part of the annulus. The liquid levels of the two fluids in the annulus depend on the reservoir physical properties and The injection velocity of the two fluids is naturally formed. For homogeneous carbonate reservoirs, the interface between the two fluids is higher when the reservoir is developed higher, and on the contrary, the interface between the two fluids is lower when the reservoir is less developed.

Detailed ways

The specific implementation of the present invention can be divided into 8 steps. The first step is to determine the fluid formula according to the formation fluid properties, temperature and pressure, and the fluid compatible with the formation can be crude oil, water, and an aqueous solution added with a reservoir improving agent, plugging agent It is recommended to use ultra-fine cement with good stability, and add additives such as retarder and viscosity reducer to it. In the second step, the KH ratio of the reservoir to be blocked and the reservoir to be protected is determined comprehensively by using data such as well logging and liquid production profile, and then the injection rate ratio of the two fluids is determined according to the viscosity of the plugging agent and the fluid compatible with the formation. Squeeze depth calculates the squeeze amount. In the third step, the pipe string is lowered into the top of the stratum to be sealed before the extrusion construction. The fourth step is to flush the well with clean water or other fluids that are not harmful to the reservoir. The fifth step is to inject a fluid compatible with the formation into the annulus at the fluid injection rate determined in the second step that is compatible with the formation. In the sixth step, when the fluid compatible with the formation reaches the bottom of the well, the plugging agent is injected at the plugging agent injection rate determined in the second step. In the seventh step, when the injection rate reaches the design requirement, the well is flushed with pressurized reverse circulation fluid that does not harm the formation. The wellhead pressure is based on the principle of ensuring the balance between the formation pressure and the wellbore. The eighth step is to shut down the well and wait for the plugging agent to condense. The seventh step is to directly open the well, artificially induce blowout to open the well for production, or remove the mechanical mining equipment for production.

Claims (1)

1. realize bottom water plugging, the purpose squeeze note technology of protection oil-gas Layer with non-selective blocking agent for one kind.It is characterized in that: utilize well logging; Information integrations such as production profile are determined the KH ratio of shutoff reservoir with the protection reservoir; determine the injection rate ratio of two kinds of fluids according to blocking agent with the viscosity of the fluid of stratum compatibility again; before the squeeze note construction tubing string is lowered to obviously above the top of desiring the shutoff stratum; injection rate ratio according to two kinds of definite fluids of front injects blocking agent from tubing string; to inject from annular space with the fluid of stratum compatibility; blocking agent is injected the stratum at tubing string with the section of going into the well and annular space bottom, and the liquid level of two kinds of fluids forms naturally according to the injection rate of reservoir properties and two kinds of fluids in the annular space.